It always lies in the equatorial plane of the discoidal body, and always unpaired in one of its axes; in the triradiate #Discoidea# it is in the axis of the unpaired principal arm and opposite to it (Pl.
Of the three feet of the basal tripod the unpaired (caudal) one is directed dorsally and backwards, the two paired (pectoral) ones ventrally and forwards.
The unpaired fins of fish were originally paired and possibly arose from the coalescence of rows of parapodia.
The unpairedsternal bone (urohyal) cannot be homologous with the entosternal, for it has no connections with the annexes.
Sometimes the ventral portions of these pads form paired or unpaired little ossifications, then generally described as intercentra; such are not uncommon on the tail.
It consists of (1) the basihyal variously called copula, or corpus linguae, or unpairedmiddle portion.
The orbito-sphenoids diverge only posteriorly, otherwise they are practically unpaired and form the median interorbital septum, which is very large in correlation with the extraordinary size of the eyeballs.
Dean concludes that "the pineal structures of the true fishes do not tend to confirm the theory that the epiphysis of the ancestral vertebrates was connected with a median unpaired eye.
Are these formed, like the unpaired fins, from the breaking up of a continuous fold of skin, in accordance with the view of Balfour and others?
It seems to possess an unpaired nose, lip cartilages in place of functional jaws, and no paired limbs; thus agreeing precisely with the lampreys and hagfishes, of which the fossil representatives have long been sought.
Like the shark there then exists no unpaired fin; the gill-slits (five?
For this reason the structure wherever found has been regarded as a rudimentary eye, and the "pineal eye" has been called the "unpaired median eye of chordate" animals.
They are also generally unpaired, a character which is however not confined to the Eudrilidae; for there are Megascolecids, such as Fletcherodrilus, and Geoscolecids in which the same unpaired character occurs.
In a number which are associated into a sub-family Eudrilacea there are two paired calciferous glands and a single unpaired one, while the paired nephridia open by a large pore on to the exterior.
The ovaries and the spermaries are only known in a few forms and appear to be unpaired and lie respectively in the fifth and sixth segments.
The cardinal veins make their appearance before the close of stage K, and very soon unite behind with the unpaired section of the caudal vein (Pl.
I find the body forming a small rod elliptical in section in the posterior region of the kidney between the dorsal aorta and unpaired caudal vein.
Posteriorly they gradually enlarge, and approaching each other in the median line, coalesce, forming an unpairedvesicle or bladder (bl.
Most investigators have however believed that there was from the first an unpaired anterior section of the heart, and that only the posterior part was formed by the coalescence of two lateral halves.
In Elasmobranchii the cerebrum is an unpaired though bilobed body, but traversed by two completely separated lateral ventricles, and without a trace of the peculiar membranous roof found in Ganoids.
From the anterior part of the region immediately behind the pharynx the air-bladder arises as a dorsal unpaired diverticulum.
In a dorsal direction the unpaired ventricle extends so as to separate the two posterior cerebral lobes.
Professor Darlste His, and more recently Koelliker, have stated that there is no such unpaired anterior section of the heart.
In addition to the above structures, which are all described by Moseley, there are a pair of small glandular tubes (f), which open with the unpaired terminal portion of the vas deferens at the generative orifice.
The two segmental ducts have united behind into an unpaired structure in an embryo of 11 millims.
It has been shewn that in Lepidosteus the unpaired fins fall into two categories, according to the nature of the skeletal parts supporting them.
He points out that the skeleton of the pelvic fin of Polyodon consists essentially of a series of nearly isolated rays, which have a strikingly similar arrangement to that of the rays of the skeleton in many unpaired fins.
The most obvious of the positive conclusions is to the effect that the embryonic skeleton of the paired fins consists of a series of parallel rays similar to those of the unpaired fins.
As stated above both the Wolffian duct and the ureters fall into an unpaired urinogenital cloaca.
These spines may be imbedded in the flesh in front of the paired or unpaired fins, or may be attached to the tail.
Forming the lower margin of the foramen magnum is a large flat unpaired bone, the =basi-occipital= (fig.
The branchiostegal rays of the two sides are united in front by an unpaired membrane bone, the basi-branchiostegal (fig.
The integument of the dorsal and ventral surfaces is commonly prolonged into longitudinalunpaired fins, supported by an internal skeleton.
Interposed between the hypo-hyals of the two sides is an unpaired somewhat triangular plate, the uro-hyal or basi-branchiostegal (fig.
In Chimaera the pelvic girdle has a flattened pointed iliac portion, and ventrally an unpaired movable cartilaginous plate which bears hooks and is supposed to be copulatory in function.
Thus on the roof of the cranium there are paired parietals, frontals, and nasals, and on its floor are paired vomers, and a median unpaired parasphenoid.
These form an unpaired opening bounded by the premaxillae.
In support of this view it may be argued that the paired and unpaired fins are often identical in structure, and that some Elasmobranch embryos do show a ridge running between the pectoral and pelvic fins.
But the warfare extends in a variety of directions, it is not confined to one sex, nor to unpaired individuals, nor need the opponents necessarily be of the same sex; it involves both sexes alike singly or combined.
Lastly, in the Octopoda the shell is represented only by small chitinous rudiments to which the retractor muscles of the head and funnel are attached; these are paired in Octopus, unpaired in other cases as in Cirrhoteuthis.
The spiracles, unpaired and seven in number, open in the median dorsal line.
But while there are no Artiodactyles with unpaired horns (save occasional sports) the Perissodactyles have more than once tried, so to speak, paired horns, which ultimately proved fatal to them.
In the latter, the male alone carried horns, and in neither sex does the unpaired median bony excrescence appear.
Very frequently the two uteri fuse above, and from the point of junction an unpaireddescending passage is formed (see Fig.
It is interesting to note that the existing Perissodactyles and Artiodactyles are to be distinguished by their unpaired or paired horns.
Both subspecies of Hyla microcephala have a long, unpaired primary note followed by 0 to 18 (usually about 4) somewhat shorter paired secondary notes.
It may be noted as a peculiarity of the mandibular arch that it is never provided with an unpaired basal element.
The second body consists of an unpaired column of cells placed between the dorsal aorta and unpaired caudal vein, and bounded on each side by the posterior parts of the kidney.
He attempts to explain the contradictory observations of other embryologists by supposing that they have mistaken the ventral ends of visceral pouches for an unpaired outgrowth of the throat.
A parallel to the unpaired medullary plate of most Chordata is supplied by the embryologically unpaired ventral cord of most Gephyrea and some crustacea.
The fact that the heart arises in so many instances as a double tube might lead to the supposition that the ancestral Vertebrate had two tubes in the place of the presentunpaired heart.
As in the types already described an unpaired vena cava inferior becomes eventually developed, and gradually carries off a larger and larger portion of the blood originally returned by the posterior cardinals.
The supraoesophageal ganglia arise as an unpaired median thickening of the procephalic lobe.
The ventral cord appears in the embryo as two independent unsegmented strands, although in a few cases (some Crustacea and Gephyrea) these cords, by an abbreviation in development, arise as an unpaired median thickening of the epiblast.
The two processes unite in the median line, and give rise in front to the anterior unpaired element of the shoulder girdle (omosternum of Parker).
Although the cerebral hemispheres vary more than any other part of the brain, they are nevertheless developed from the unpaired cerebral rudiment in a nearly similar manner throughout the series of Vertebrata.
As pointed out by Mivart, a longitudinal bar is also occasionally formed to support the cartilaginous rays of unpaired fins.
The fact of the organ being unpaired in Elasmobranchii and paired in the Amniota is of no importance, as is shewn by the fact that part of the organ is unpaired in the Rabbit.
Anteriorly the right vein atrophies and the left continues forward the unpairedposterior section.
The gamekeeper said during breeding season he had never observed a single or unpaired partridge.
Perhaps the best experiment, for my purpose, would be to colour a young unpaired male and turn him with other pigeons, and observe whether he was longer or quicker than usual in mating.
For additional description of the unpaired fins on the type, K.
The Diplocercinae include those coelacanths having two large unpairedbones in the endocranium (at present this includes Diplocercides Stensioe, Nesides Stensioe and Euporosteus Jaekel).
The sphenethmoid region was certainly not a large, unpaired unit as in the Diplocercines.
Members of this subfamily differ from those of the subfamily Diplocercinae in having several paired and unpaired elements in the sphenethmoid region of the endocranium, instead of only one larger ossification.
An upper lip or labrum is formed as an unpaired organ in the line between the procephalic lobes.
The greater part of the original outgrowth remains as the unpaired duct of the two glands[117].
The anterior mass is formed as an unpaired anterior thickening, followed by two lateral thickenings.
In the first place the paired eyes are formed at each side of and behind the unpaired eye, secondly the posterior pair of maxillae is formed though it always remains very rudimentary.
There also appear close to the sides of the unpaired eye two conical bodies, which correspond with the frontal sense organs of the Phyllopods.
On the dorsal surface of the body the unpaired eye is still present, but on each side of it traces of the stalked eyes have appeared.
In the cephalic region two small papillae (fr) are now present at the front of the head close to the unpaired eye.
At the anterior extremity are situated a pair of refractive bodies (r) which lie above an unpaired organ which may be called the urn.
An unpaired eye is situated on the ventral surface of the head, and immediately behind it there springs a more or less considerable upper lip (lb), which resembles the Phyllopod labrum rather than that of the Copepoda.
Before the hatching of the embryo takes place this mesentery is continued backwards so as to divide the primitively unpaired caudal part of the body cavity in the same way.
In front of the oral opening an unpaired upper lip is developed.
In the Tracheata they arise from the division of an unpaired ventral plate.
The unpaired mesoblastic plate becomes in all forms very soon divided into two mesoblastic bands.
The mouth is ventral, and placed in the middle line between the second pair of antennae and the mandibles: it is provided with an unpaired upper lip.
Section through the unpaired cerebral rudiment during stage O, to shew the origin of the olfactory lobe and the olfactory nerve.
Rudiment of septum which will grow backwards and divide the unpaired cerebral rudiment into the two hemispheres.
Posteriorly the skull consists of four bones: an unpaired median dorsal supraoccipital, an unpaired median ventral basioccipital and two lateral exoccipitals.
Unpaired tentacle situated well caudad, more slender than the paired ones but nearly as long.
Unpaired tentacle situated between eyes in line connecting their centers, nearly of same length and size as the first tentacular cirri and about as long also as prostomium; annulate.
When highly developed, it contains unpaired ganglia and nerves, but may be represented only by an indefinite plexus (earthworm).
Footnote 70: As Wilson has proved, the unpaired body is not a universal feature even in those orders in which it has been observed.
It is to be noted that the dorsal aorta retains the probably primitive unpaired condition, except for a very short extent at its anterior end, where it is split so as to form two short aortic roots.
That the unpaired olfactory organ of existing Cyclostomes has passed through, in their ancestors, a paired condition such as exists in other vertebrates, is indicated by the fact that it retains a pair of olfactory nerves.
Mouth-parts for piercing and sucking, consisting of paired mandibles with serrate margins and unpaired labrum.
Rostrum (= labium + labial palpi) rather long but very weak and pale, consisting of two or three segments inclusive of the unpaired basal segment.
To others it suggests an eye and they regard it as the remnant of an unpaired ocellus possessed by the ancestral flea.
In our study of a frog we find that the mouth cavity has two unpaired and four paired tubes leading from it.
It consists of a bony framework, the vertebral column which protects the spinal cord and certain attached bones, the ribs, with other spiny bones to which the unpaired fins are attached.
The appendages of the fish consist of paired and unpaired fins.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "unpaired" in a variety of sentences. We hope that you will now be able to make sentences using this word. Other words: absolute; alone; celibate; lone; odd; only; singular; sole; unique; unmatched
