East coast marine shells; descriptions of shore mollusks together with many living below tide mark, from Maine to Texas inclusive, especially Florida eastcoastmarines00rome Year: 1937 20 EAST COAST MARINE SHELLS and known as the CAPITULIFORM TOOTH, often shaped like the blade bone of a shoulder of mutton. The central tooth is present and often small. (g) DOCOGLOSSA. Compared with the Rhipidoglossa the members of this group possess a radula with a few strong teeth. Only three fam- ilies, Acmaeidae, Patellidae (Fig. 28) and Lepetidae are placed here. The number of teeth in a row range from
East coast marine shells; descriptions of shore mollusks together with many living below tide mark, from Maine to Texas inclusive, especially Florida eastcoastmarines00rome Year: 1937 20 EAST COAST MARINE SHELLS and known as the CAPITULIFORM TOOTH, often shaped like the blade bone of a shoulder of mutton. The central tooth is present and often small. (g) DOCOGLOSSA. Compared with the Rhipidoglossa the members of this group possess a radula with a few strong teeth. Only three fam- ilies, Acmaeidae, Patellidae (Fig. 28) and Lepetidae are placed here. The number of teeth in a row range from two to twelve. The rib- bon is often very long, the teeth heavy, deep-horn color, and some- what opaque. The arrangement is somewhat compli- cated with a mul- tiplication of identical cen- trals. In some cases there is no true central tooth. Lateral and marginal teeth may be lost, when present they are few in num- ber. Outside of the Gastropoda, which have just been discussed, the radula occurs in the Amphineura or coat-of-mail shells. In these it is unique, be- ing composed of thick and deeply colored teeth, greater in number than in the Docoglossa. In the Scaphopoda, or tusk shells, the radula is large and pe- culiar. It occurs in Dentaliiim with a broad plate representing the central tooth. The one lateral tooth is robust, arched, and a little cusped; the marginal a large quadrangular plate, quite simple. The formula for the Scaphopoda would be Fig. 28 Radula of Patella Patella vulgata L., showing the normal position of the radula, irtiich is doubled back in a bow; the shell has been removed, and the iriiole visceral mass is turned for- ward, exposing the dorsal surface of the muscular foot; gr, longitudinal groove on this surface; i, i, intes- tine; 1, liver; m, m, mantle edge; mu, muscles (cut through) fastening the vis- ceral mass to the upper sides of the foot; ov, ovaiy; r, radula; , upper or dor- sal surface of the foot. Among the Cephalopods the radu- la
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