Defn: A division of marine gastropod mollusks in which the radula are converted into poison fangs.
Defn: A division of gastropod mollusks having the teeth of the radula arranged in long transverse rows, somewhat like the barbs of a feather.
As before remarked, the radula is made up of parallel rows of teeth, the whole area being usually divided into five longitudinal rows, each row differing from the one next to it.
It is formed from a layer of cells in the posterior part of the buccal sac, called the radula sac, and new teeth are constantly forming here to take the place of those which have become worn by use.
Thus in some species of our common snails there are seventy-one teeth in a single row, and the whole radula is made up of a hundred rows of teeth, making a grand total of seventy-one hundred teeth in the mouth of a single snail!
The radula is placed in an organ called the buccal sac and occupies a position in the sac analogous to that of the tongue in a cat or dog, viz.
Hubrecht in 1881 of a typical molluscan radula and odontophore in a new genus Proneomenia, allied to Neomenia, showed that the whole group belonged to the Mollusca.
It is a curious fact that in the original type Neomenia the radula is entirely absent, as it likewise is in several genera of Proneomeniidae.
Each transverse row of teeth of the radula contains 17 teeth, one of which is median, while the second and the fifth on each side are enlarged.
Elongated, cylindrical, rounded at both ends; thick cuticle with acicular spicules; radula polystichous or wanting.
Short and truncated in front; thick cuticle, often without papillae; gills and radula present.
In other species theradula is more of the usual type consisting of several transverse rows of two or three teeth each.
Immediately behind the opening of the salivary glands there appears on its floor a swelling which becomes the odontophore, and behind this a pocket of the stomodaeal wall forms the sheath of the radula (figs.
From the above statements it would appear that Kowalevsky holds that the oesophagus and radula sack are both derived from the walls of the archenteron and not from the stomodaeum.
At a subsequent period there are developed in the oral region of the stomodaeum the radula in a special ventral pit, and the salivary glands--the latter as simple outgrowths.
The three following families have neither radula nor jaws, and are therefore called Aglossa.
Shell external, spiral, generally ornamented with ribs; borders of aperture thin and not reflected; radula with square teeth; genital ducts without accessory organs.
Shell internal, or absent; mantle restricted to the anterior and middle part of the body; radulawith squarish teeth.
Radula with a median tooth and three teeth on each side of it.
Radula with a median tooth and a single tooth on each side of it.
Shell elongated, with long siphon; lateral teeth of radula multicuspidate.
Radula with elongated and pointed teeth, like those of the Agnatha; a jaw present.
In the radula there is a single central tooth or none.
Cephalic shield ending posteriorly in a median point; shell internal, largely membranous; no radula or stomachal plates.
The radula has a number of uniform teeth on each side of the median tooth in each transverse row.
Radula with very numerous marginal teeth arranged like the rays of a fan.
Radula narrow with one lateral tooth on each side, and one median tooth or none.
In the radula there are three teeth on each side of the median tooth in each row, except in Gonatus, in which there are only two lateral teeth, and the Cirrhoteuthidae, in which the radula has entirely disappeared.
A labial commissure arises by a double root from the cerebral ganglia and gives off a stomatogastric commissure, which passes under the pharynx immediately behind the radula and bears a buccal ganglion on either side.
In front of the radulais the so-called tongue, a fleshy projection corresponding to the sub-radular organ of other Mollusca.
A division of gastropod mollusks having the teeth of the radula arranged in long transverse rows, somewhat like the barbs of a feather.
A division of marine gastropod mollusks in which theradula are converted into poison fangs.
Illustration: Portion of the radula of /Imbricaria marmorata/.
Conus/ is accused of having a poison-gland connected with the radula and of having shown vicious traits when captured.
The radula is a most important organ, and is a unique possession of /Mollusca/, except the pelecypods, or bivalves.
The radula has been the subject of much study by conchologists, and has furnished the basis for an arrangement of the numerous sections of gasteropods into somewhat well-defined groups.
Illustration: Three rows of teeth from the radula of /Fasciolaria trapezium/.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "radula" in a variety of sentences. We hope that you will now be able to make sentences using this word.
