Radula

Definition and stakes

A. H. Cooke,  The Cambridge natural history, Vol… (1895)

“ The first step is to obtain the radula. Dissection is easy in species of a reasonable size. On opening the head from above, so as to lay open the floor of the mouth, the radula itself is seen in most of the marine species, though in others it is contained in a sort of proboscis; and in the Pulmonata and others the student will find the buccal mass, with commonly a brown mandible at its front end, and the lingual ribbon in its hinder part. ”
Source: Gutenberg

A. H. Cooke,  The Cambridge natural history, Vol… (1895)

“ In closely allied species the differences exhibited are naturally but slight, but in well-marked species the differences are considerable. The radula, therefore, serves as a test for the distinction of genera and species. For instance, in the four known recent genera of the family Strombidae, viz. Strombus, Pteroceras, Rostellaria, and Terebellum, the radula is of the same general type throughout, but with distinct modifications for each genus; and the same is true, though to a lesser extent, for all the species hitherto examined in each of the genera. ”
Source: Gutenberg

A. H. Cooke,  The Cambridge natural history, Vol… (1895)

“ Fig. 126.—Four rows of teeth from the radula of Vermetus grandis Gray, Andamans. × 40.
In Homalogyra the radula is much degraded, the central tooth is large and triangular on a broad base, the lateral is represented only by a thin oblong plate, and the uncini are absent. In some species of Jeffreysia the uncini are said to be absent, while present in others. Lamellaria has lost both its uncini, but the radula of the allied Velutina is quite typical. A peculiar feature in this group is the tendency of the marginals to increase in number.
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Source: Gutenberg

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