The aperture, or opening, being turned towards you, the front of a univalve is seen; reverse it, and you see the back.
As I have observed that you have been very diligent in studying Lamarck since our last lesson," said Mr. Elliot, "I propose to make you acquainted with the variations in the univalve genera.
The genus Scalaria is one of the most elegant among univalve shells.
The teeth in univalve shells, as the cowry, are ridges upon the aperture.
The lid is not, however, like the tongue-ribbon, an essential feature of the structure of every univalve mollusc.
Their tails are soft, and they thus require protection: they choose the dried shell of some univalve mollusc and live in it (Fig.
E is Spirorbis, a minute form with a coiled tube, which looks at first sight like a small univalve shell.
A curious suggestion has been made with regard to the lids of univalve shell-fish; namely, that the snapping to of the lid is capable of producing a sound, which may perhaps be audible at a distance under the water.
It is possible that these exceptional instances were the work of a young and inexperienced univalve mollusc, or a stupid one.
The snail proper bears a typical univalve shell: though in its relatives (the slugs), the shell is more or less suppressed.
Everyone who has spent a little time in naturalising on the shore, has noticed how often you may find univalve shells, such as those of the whelk and periwinkle, with the top of the shell knocked off.
D] Not only are there special instances in which it is greatly modified, but also there are whole groups of univalve molluscs in which it is absent.
The dorsal surface of a spiral univalve is that which is seen when the aperture is turned from the observer.
A term applied to the aperture of a univalve shell, when it is spread out or widened into a flat surface, or digitations.
The peritreme of a univalve shell is said to be entire when not interrupted by canals or by the body whorl.
The aperture of an univalve shell is said to be effuse when there is a notch in the margin which would suffer a liquid to escape, and thus prevent it being filled to the brim.
The spire of an univalveshell is said to be turrited when the whorls of which it is composed are regulated so as to have the appearance of little turrets rising above each other, as in Mitra, fig.
A term which is applied by some conchological writers to the spire of an univalve shell when it consists of numerous whorls drawn out into a telescopic form.
The elongated hollow process which terminates the aperture anteriorly of some univalve shells.
This term is applied by conchologists when the apex of the spire of an univalve shell is rounded like a teat and not spiral up to the extreme point; as the apex of Cymba, fig.
A term applied to the prominences on the columellar lip of some univalve shells, particularly in the sub-family of Volutidae.
The posterior extremity of the aperture of a spiral univalve shell, is that nearest to the spire.
The cone or pyramid produced in a non-symmetrical univalve by its oblique revolution downwards from the apex or nucleus.
That edge of the aperture of an univalveshell which is near to the imaginary axis, as distinguished from the outer lip, or that which is on the opposite side.
This must be distinguished in the first instance from another kind of calcareous covering, which in some univalve shells serves to close the aperture during a certain portion of the year.
The apicial extremity of the aperture of a univalve shell, is that which is nearest to the apex of the spire.
They constitute the most numerous order of Cephalous Molluscs, comprehending nearly all the univalve spiral shells, and many others which are simply conical.
The Gasteropoda are extremely numerous; most of them haveunivalve shells, but many of them have none, as the Garden Slug (Limax, fig.
Practically all the gasteropod or univalve shells that will be taken by the ordinarily expert collector along the shore are prosobranchs.
Putting aside the bivalves, the univalveor gasteropod shells remaining should be closely examined for the purpose of becoming acquainted with their various conchological features.
Suture^: The line of junction of the successive whorls of a univalve shell, or the line of closure of the opposite valves of a bivalve shell.
Columella^: An upright pillar in the center of most of the univalve shells, round which the whorls are convoluted.
The largest univalve north of Hatteras, most easily recognized by its pear-shaped shell, with simple suture and brilliant vermilion aperture.
A first lesson in classification of the /Mollusca/ may be taken by dividing the results of the first day's collecting of univalve shells into groups according to these prominent shell-characters.
A genus of large univalve mollusks abundant in the arctic seas.
A genus of fossil univalve shells, believed to belong to the Heteropoda, peculiar to the Paleozoic age.
The prolongation of certain univalve shells containing the canal.
The imbedded shells are chiefly casts, many of them of univalve mollusca, which are usually very rare in the white chalk of Europe.
Euomphalus is a characteristic univalve shell of this period.
On the other hand, Voluta, Fasciolaria, and other genera of univalve shells, usually met with only in tertiary strata, occur.
The general absence of univalve mollusca in the white chalk is very marked.
The univalve shells most characteristic of fresh-water deposits are, Planorbis, Limnaea, and Paludina.
Thirria; Nerinaea being an extinct genus of univalveshells (Figure 325) much resembling the Cerithium in external form.
A volution, or turn, of the spire of a univalve shell.
The hermit crabs usually occupy the dead shells of various univalve mollusks.
Applied to the line where the whorls of a univalve shell join one another; also to the lines made upon the exterior of the shell of a chambered Cephalopod by the margins of the septa.
The genus ofUnivalve Molluscs comprising the Cowries.
Univalve Molluscs, such as Cowries and Volutes, which are otherwise exclusively Tertiary or Recent.
Defn: One of the prominent ridges or ribs extending across each of the whorls of certain univalve shells.
Any marine univalve shell of the genus Rostellaria; -- called also spindle stromb.
Defn: A large, ornamental, marine, univalve shell of the genus Melo.
Defn: A large, handsomely colored, marine univalve shell (Fasciolaria tulipa) native of the Southern United States.
Defn: One of the whorls of a spiral univalve shell.
Defn: A marineunivalve shell of the genus Pyrula, or Ficula, resembling a fig in form.
Defn: Any large marine univalve shell of the genus Triton.
Defn: Having one valve; as, a univalve shell or pericarp.
A seam, or impressed line, as between the segments of a crustacean, or between the whorls of a univalve shell.
Defn: One of a group of univalve shells, having a large aperture or mouth.
Defn: A genus of small, polished, marineunivalve shells, native of all warm seas.
It is interesting to note the location of this hole, which is invariably over the softest and plumpest part of the victim, near the lungs, showing that the cannibalistic univalve is very clever in its mode of attack.
The univalve has a shell-secreting mantle and organs resembling those of the bivalves, only differently placed.
Those shown on the upper part of Figure 94 are univalves, and if we make a section of a univalve (Fig.
Before passing on to the univalve molluscs, we must refer briefly to a group of animals that are enclosed in bivalve shells, and which were once included with the Mollusca, but are now made to form quite a distinct group by themselves.
Among the former are the empty shells of both univalve and bivalve molluscs, some of which are more or less worn by the action of the waves, while others are in splendid condition for examination and study.
Most univalve shells are covered with epidermis, but in some instances the animal, when extended, surrounds the exterior of the shell with its mantle, as do the cowries, and then the outside of the shell is always glazed.
But before we go further, it may be well to point out the names given to different parts of a univalve shell.
The former is the cast of a Trigonia shell; the latter, that of a tall spired univalve (Cerithium).
In the next higher class of the Gasteropoda, or marine univalve shells, the sexes are either united or separate.
One of a group of univalve shells, having a large aperture or mouth.
In passing up this valley, an almost never-failing object of interest was furnished by the univalve shells found along its banks, and by the variety in size, shape, and color which they exhibited.
Among the fragments of rock thrown out, are impressions of bivalve and univalve shells, with an impression resembling the head of a trilobite.
Some of these are most vivid in their shapes and ray-like markings, particularly the univalve shells.
Bivalve and univalve mollusca seem to be rare at the greatest depths; but starfishes, sea urchins and other echinoderms, zoophytes, sponges, and protozoa abound.
It has long appeared to me that in the tropics as well as in the temperate zone the species of univalve shells are much more numerous than bivalves.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "univalve" in a variety of sentences. We hope that you will now be able to make sentences using this word.
