. Annual report of the regents of the university of the state of New York on the condition of the State Cabinet of Natural History and the historical and antiquarian collection annexed thereto. h the exception that theventral valve is concave ; which, in lesser degree, is true likewise of Strep-torhynchus ivoohoorthana and S. pandora. The Strophomena defiecta andS. deltoidea, Conrad ; the S. filitexta, S. planumhona and >S^. planoconvexa,Hall ; and S. sinuata of de Verneuil, have the ventral foramen par-tially or entirely closed, and have^ otherwise externally the characters ofstrias of Str
. Annual report of the regents of the university of the state of New York on the condition of the State Cabinet of Natural History and the historical and antiquarian collection annexed thereto. h the exception that theventral valve is concave ; which, in lesser degree, is true likewise of Strep-torhynchus ivoohoorthana and S. pandora. The Strophomena defiecta andS. deltoidea, Conrad ; the S. filitexta, S. planumhona and >S^. planoconvexa,Hall ; and S. sinuata of de Verneuil, have the ventral foramen par-tially or entirely closed, and have^ otherwise externally the characters ofstrias of Streptorhynchus.* The interior of the ventral valve, in two atleast of these species, show dental lamellae of moderate strength, whichare continued in an elevated border nearly surrounding the muscular im-pression. In the dorsal valve of S. filitexta, we have a bifid cardinal processas in typical forms of Streptorhynchus, but scarcely so much developedas in 8. subplana ; while the teeth-sockets are very shallow, and the socket-plates very little developed. The muscular impression of this valve is likethat of typical Streptorhynchus, and unlike that of typical species ofStrophomena. Fig. When we compare the bifurcating cardinal process of Streptorhynchuswith that of Strophomena,! we find the latter consisting of a double pro-cess, or of two toothlike processes, which are inclined inwards, flattened, * To these may probably be added some other species of resupinate character,t Taking Strophomena rngosa and S. alternata as illustrations. CONTRIBUTIONS TO PALiEONTOLOGY, 65 and striated on their exterior faces, but not * grooved or bidentated towards the extremity of their outer surface as in Streptorhynchus. Hereagain, however, it becomes necessary to distinguish the cardinal process ofStreptorhynchus from that of Strophodonta ; for the Ij^tter is a bi-furcating process, and the divisions are bidentate or grooved on their outerface. Aside from the crenulated hinge-line, which is u
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectscience, bookyear1853
