In the less highly specialized groups of fishes the pectoral fins are close behind the head, the pelvic fins in the region of the cloacal opening.
The genital pores mentioned must not be confused with the abdominal pores, which in many adult fishes, particularly in those without open peritoneal funnels, lead from coelom directly to the exterior in the region of the cloacal opening.
Its hind-end elongates till it comes into connection with, and opens into, the cloacal section of the hindgut[258].
In Acipenser and Amphibia thecloacal region is indicated as a ventral diverticulum of the mesenteron even before the closure of the blastopore.
The segmental ducts in the larvae open behind into the cloacal section of the alimentary tract.
The middle division of the mesenteron, forming the intestinal and cloacal region, is primitively a straight tube, the intestinal region of which in most Vertebrate embryos is open below to the yolk-sack.
The collecting tubes of the latter do not enter the Wolffian duct directly, but bend obliquely backwards and only fall into it close to its cloacal aperture, after uniting to form one or two primary tubes (ureters).
It soon acquires a lumen, and joins the cloacal section of the alimentary tract before the close of foetal life.
From the ventral wall of the cloacal section, there grows out the bifid allantoic bladder, which is probably homologous with the allantois of the higher Vertebrata.
In all Vertebrata thecloacal section of the alimentary tract which receives the urinogenital ducts is placed in communication with the exterior by means of an epiblastic invagination, constituting a proctodaeum.
At the other, placed on the dorsal surface between the nervous system and the elaeoblast, is formed the cloacal aperture.
In front of this point it rapidly dilates again, and, after becoming fairly wide, opens on the dorsal side of the cloacal section of the alimentary canal just behind the anus (D al).
That part of a bird, or the feathers, surrounding the cloacal opening; the under tail coverts.
The anal opening of certain invertebrates and fishes; also, the external cloacal opening of reptiles, birds, amphibians, and many fishes.
The hindgut is cylindrical in cross section and of about the same diameter throughout, except for a slight enlargement in the cloacal region.
Figure 5H represents a section through the cloacal region, cl, showing the openings into the cloaca of the Wolffian ducts, wdo.
No sign of a cloacal invagination could be made out with certainty.
This arrangement facilitates the internal fecundation of the female without copulation, the female absorbs the spermatozoa by squeezing them out of the spermatophore between the cloacal lips.
On the intestine near the cloacalopening note a pair of glandular structures, the caeca.
From the duodenum the small intestine or ileum extends with many convolutions to its exit through the cloacal aperture.
With a pair of scissors cut just beneath the skin anteriorly from the cloacal opening to the angle of the lower jaw.
The eggs pass from the egg-gland into the body-cavity, where they are caught in the upper end of the oviduct and carried down and out through the cloacal opening.
The bronchus opens at once into the more or less elongate, usually single lung, with or without a rudiment of a second, which seems to be constantly the left; in some snakes the lung extends nearly to the cloacal region.
The male then endeavours to bring the two anal orifices together, and when he has succeeded in getting the female to distend her cloacal opening, the intromittent organs are suddenly everted into the vagina.
Just before oviposition the female curves the base of the tail upwards, in order to extend the cloacal opening.
The latter is a precocious hypertrophy of the cloacal bladder found in Amphibia, with the function of embryonic respiration.
In Lizards they are pouches of the skin at the sides of the cloacal opening.
The structure of the cloacalprotuberance of the Vesper Sparrow (Pooecetes gramineus) and certain other passerine birds.
The penis consists of a pair of slender, clavate, chitinous spicules, the ends of which protrude from the cloacal aperture at the root of the tail.
The penis is a single chitinous spicule, the end of which is usually seen projecting from the cloacal aperture.
It is possible, however, that besides these many of the other mammalian teeth found in the Jura and Chalk systems, which are still generally ascribed to Marsupials, in reality belong to Cloacal Animals.
Moreover, the coracoid bones are much more strongly developed in the Cloacal animals than in the other Mammalia, and are connected with the breast bone.
First Sub-class of Mammalia: Forked orCloacal Animals (Monotrema, or Ornithodelphia).
Marsupials, in these anatomical respects, stand midway between Cloacal and Placental animals.
All the fossil remains of Mammals known to us from the Secondary epoch, belong either exclusively to Marsupials, or partly perhaps to Cloacal animals.
This pouch is supported by two characteristic marsupial bones, also existing in Cloacal animals, but not in Placental animals.
The supposed polyps would only form a cloacal system for the use of the sponge colony.
Professor Semper has since discovered another species of these, which he has dedicated to the illustrious physiologist of Berlin, and which he found attached to the cloacal sac of the Holothuria edulis.
The posterior extremity of the male is furnished with a bilobed caudal appendage, its cloacal or anal aperture being situated between these divergent appendages.
This surrounds thecloacal outlet, the latter concealing a double spiculum.
The taxonomic significance of cloacal bursae in turtles.
Cloacal bursae seem to be vestigial in the species of Terrapene possessing them and to be of little or no use as respiratory structures (except perhaps in T.
Tail terminating in flexible point; penis exposed; cloacal opening extending beyond posterior edge of carapace; tail olive above bordered by blackish marks; few black dots laterally on left side.
The hind feet are used alternately; cloacal water may be used to facilitate digging or to provide a suitable substrate for the eggs.
Some females of spinifer and muticus that exceed the maximum size attained by males have the tip of the tail and cloacal opening extending a short distance beyond the posterior edge of the carapace.
Tail terminating in flexible point; penis partly exposed; cloacal opening extending beyond posterior edge of carapace; tail having dorsal grayish band flanked by interrupted blackish lines; dark marks encroaching ventrally at tip of tail.
The water after passing through the branchial network is received into narrow passages and conducted to a larger cavity--the cloacal or atrial chamber.
As a rule, the earlier stages of the embryo are passed inside the cloacal chamber, though in some the development occurs outside the body.
Ectoderm and entoderm in this region with the intervening mesodermal layer form the cloacal membrane (Fig.
Behind this point the ventral cloacal wall is formed by the cloacal membrane.
These two portions of the original cloacal membrane become perforated separately, the uro-genital before the anal.
Each of these canals is still closed caudad by its respective portion of the cloacal membrane, now divided into an anal and uro-genital segment.
The hindgut extends from its junction with the midgut to the cloacal or anal opening.
In birds, reptiles, amphibia and many fishes (especially the Plagiostomata) this cloacal formation is the rule.
A second fold forms the distal limit of the urodaeum and separates it from the lowest cloacal compartment, the proctodaeum.
When these folds have reached the cloacalmembrane they complete the separation of the cloaca into two adjacent canals.
The terminal portion of the alimentary canal, in entering the cloaca, forms an expanded upper cloacal compartment for the accumulation of the excreta, called the coprodaeum.
The ventral wall of the cloaca has been divided to the left of the median line and turned over to the right, carrying with it the cloacal opening of the bladder.
A large dead skink left on the metal strip in direct sunlight for five minutes had a cloacal temperature of 45.
She then moves away, pressing her cloacal region against the ground.
His hind leg then rests over the base of her tail and the right angle formed by the laterally projecting hind leg and the tail in each lizard aids to guide their hindquarters into position so that cloacal contact is established.
Other favorite sites of attachment are: about the insertion of the hind limb, about the cloacal opening, on the eyelids and on the toes.
In front of this point it rapidly dilates again, and, after becoming fairly wide, opens on the dorsal side of the cloacal section of the alimentary canal just behind the anus (fig.
The cloacal involution, relatively to the cloaca, recedes backwards.
The figure shews the solid anterior extremity of the cloacal involution.
The posterior part of each segmental duct acquires an opening into the cloacal section of the alimentary tract.
Section through the cloacal region of an embryo belonging to stage P.
Elsewhere the wall of the cloaca and cloacal groove are merely in contact but do not communicate.
Three sections through the cloacal region of an embryo belonging to stage O.
The perforation of the cloacalinvolution is carried slowly forwards, so that the opening into the cloaca, though retaining its slit-like character, becomes continuously longer; by stage Q its size is very considerable.
By stage O all the ureters have become prolonged up to the cloacal end of the Wolffian duct, so that the anterior one has a length equal to that of the whole kidney proper.
The thick-walled stalk of the vesicle is connected with the cloacal section of the alimentary tract by a very narrow thin-walled tube (Pl.
Cl, Cloacal or pallial chamber of Neomeniae and Chaetoderma.
Aplacophora without distinct ventral groove, with single median unisexual gonad, with differentiated hepatic sac, and with cloacal chamber furnished with two bipectinate gills.
The body is worm-like and cylindrical, the posterior half a little thicker than the anterior; the posterior extremity forms the enlarged funnel-like branchial or cloacal chamber.
In Neomeniidae and most of the Parameniidae there is a circlet of gills on the inner walls of the cloacal chamber.
Short, truncate in front and behind; cloacal orifice transverse; gills present; rather thin cuticle; no radula.
The downward prolongation of the segmental duct to join the posterior or cloacal extremity of the alimentary tract (9b).
Between the mesosomatic region represented by the vagus, and the cloacal region, there existed a small metasomatic region, represented by the pronephros, with its segmental duct, as already discussed in Chapter XII.
Similarly, on the invertebrate side, all those forms which resembled Limulus must have possessed a very short region between the branchial and cloacal parts of the body.
Associated with the large intestine is the bladder, the whole system arising from the original cloacal region; the vagus never supplies the bladder, its motor nerves belong to the sacral outflow.
These muscles belong really to the muscles in connection with the Muellerian and Wolffian ducts and skin, not to the cloacal region.
Mr. Wells I have encountered in print, where he says that Joyce has a cloacal obsession, but he also says that Mr. Joyce writes literature and that his book is to be ranked with the works of Sterne and of Swift.
Cloacal smears from the racers examined usually showed an abundance of ciliate protozoans, either parasites or commensals, and occasionally nematode worms.
After a sudden change in the female's position, the rear of the male's body would perform groping movements along that of the female until his cloacal region was approximately opposite hers.
Also, sperm samples were often taken from males at different times throughout the season of activity, and cloacal samples from females occasionally were checked for sperm as evidence of recent copulation.
Cycle of the Male Cloacal smears indicate that males mature sexually and first produce sperm in August and September when they are a little more than a year old.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "cloacal" in a variety of sentences. We hope that you will now be able to make sentences using this word.
