. Elements of conchology / Prepared for the use of schools and colleges. Mollusks. This family is divided into Tridacna, Chama, Isocardia, &c. 27. The Tridacna have an' equivalve shell, which is elon- gate and gaping in front, or its edges are dentate {fg. 103). Their internal orga- nization is remarka- ble in several particu- lars. The valves have only a single adductor muscle. The mantle is widely open in front, to give passage to the byssus, and a little beneath the an- terior angle presents Fig. 103.—TRIDACNA. another opening, by which water is conveyed to the branchiae; and the third
. Elements of conchology / Prepared for the use of schools and colleges. Mollusks. This family is divided into Tridacna, Chama, Isocardia, &c. 27. The Tridacna have an' equivalve shell, which is elon- gate and gaping in front, or its edges are dentate {fg. 103). Their internal orga- nization is remarka- ble in several particu- lars. The valves have only a single adductor muscle. The mantle is widely open in front, to give passage to the byssus, and a little beneath the an- terior angle presents Fig. 103.—TRIDACNA. another opening, by which water is conveyed to the branchiae; and the third open- ing, which corresponds to the anus, is situate near the middle of the inferior border. To this genus belongs an enormous shell of the Indian Ocean, known under the vulgar name of the Holy-water Pot; it adheres to the rocks by its byssus, which is so large sometimes that an axe is required to cut it, and the shell itself occasionally weighs over three hundred pouuds. 28. The Chama have an ir- regular, equivalve shell, which is usually lamellar and rough ; ihey live attached to rocks, coral, &c., like oysters, and they have a small foot bent like that of man {fig, 102). 29. ThelsocARDLE (^0^.104), on the contrary, have a free, regular, convex shell with spirally curved summits, divided anterior- ly. A large, smooth, red species, the Chama cor, inhabits the Fig. 104. ISOCARDIA. 27. What are the characters of the genus Trida'cna ? 28. How is the genus Chama distinguished ? (Chama,—pronounced fca'wo,—fiom tlie Greek, chad, I gape.) _ 29. What are the characters of the genus Isoca'rdia ? (Isocardia, from the Greek, \RUi>, iike, and kardia, a heart,—heart-shape.). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Ruschenberger, W. S. W. (William Samuel Waithman), 1807-1895; Comté
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectmollusks, bookyear184
