. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 710 CONCHIFERA. The teeth are commonly simple and conical; occasionally they are flattened either lengthwise or transversely. In a considerable number of species they are grooved to different depths on their summits, and the teeth are then said to be bifid (e, Jig. 365). There are other parts still which present themselves upon the cardinal edge, and of which it is important to have a sufficient know- ledge,—namely, those destined for the implan- tation of the ligament when it is external; to these parts the name of nymp
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 710 CONCHIFERA. The teeth are commonly simple and conical; occasionally they are flattened either lengthwise or transversely. In a considerable number of species they are grooved to different depths on their summits, and the teeth are then said to be bifid (e, Jig. 365). There are other parts still which present themselves upon the cardinal edge, and of which it is important to have a sufficient know- ledge,—namely, those destined for the implan- tation of the ligament when it is external; to these parts the name of nympha is given. These form two callosities more or less promi- nent, which are seen along the posterior and superior edge of the shell. When the ligament is internal, it rests upon a cavity generally pro- minent towards the interior of the valves, and designated by the name of cuitteron or spoon- shaped cavity. This cuilleron is generally situated in the centre (c, d, fig. 367) of the Fig. hinge ; sometimes, however, it becomes a little oblique, elongated, narrower, and runs in the direction of the posterior and superior edge. When we direct our attention to the external forms of the bivalve shells, we observe numerous modifications, of the principal of which it is necessary to take some notice. In a consi- derable number of species the two valves are alike, when the shell is said to be equivalved. When one of the valves is larger than the other it is of course inequivulved; to constitute it so it is not necessary that the shell should be irregular. A regular shell is that which at liberty always presents the valves alike in all the individuals of the species; an irregular shell is not only inequivalved, but farther, the whole of the individuals of the same species are not exactly of the same form, and want the same peculiarities of external conformation generally. The Oysters are inequivalve and irre- gular shells ; the Corbules are inequivalve and regular shells; the Ve
Size: 1323px × 1889px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, booksubjectanatomy, booksubjectphysiology, booksubjectzoology
