The Cambridge natural history . hinge-teeth (Fig. 329, t)in the ventral valve, which fit into corresponding sockets in theopposite valve. Some genera have the teeth very rudimentary,or have lost them altogether. The teeth are frequently sup-ported by dental plates, and the sockets by socket plates ( Conchidium, Figs. 324, 325). A few genera with a longhinge line have the whole of it denticulated (Stropheodonta). Inthe dorsal valve medianly close under the hinge line is a shellyprotuberance-—the cardinal process —to which the diductormuscles are attached. It is sometimes of great length and
The Cambridge natural history . hinge-teeth (Fig. 329, t)in the ventral valve, which fit into corresponding sockets in theopposite valve. Some genera have the teeth very rudimentary,or have lost them altogether. The teeth are frequently sup-ported by dental plates, and the sockets by socket plates ( Conchidium, Figs. 324, 325). A few genera with a longhinge line have the whole of it denticulated (Stropheodonta). Inthe dorsal valve medianly close under the hinge line is a shellyprotuberance-—the cardinal process —to which the diductormuscles are attached. It is sometimes of great length andforked {Stringocephcdus, Fig. 326), or tripartite, or even quadri-partite ; but in Rhynclionella and some other genera it is rudi-mentary. VOL. Ill 2 K 49S FOSSIL BRACHIOPODA A hinge area (Fig. 334, ) is often present on one or bothvalves, and may be of great size, as in Clitamhunites, but inProductus it is wholly absent. In those genera that possess it atriangular fissure—the deltidial fissure —frequently traverses.
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
