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1320 



TERTIARY FAUNA OF FLORIDA 



Subfamily GEMMING. 



This group includes small species of Veneridse which are characterized by 

 viviparity and carry the young, for a considerable period, like Spharium, 

 within the perivisceral chamber. They have, as a rule, purple and white colora- 

 tion, if any, and a smooth or concentrically striated surface. They live in sand 

 or mud in moderate depths of water on both coasts of North America, and 

 have not been identified from any other region. Other small Veneridce may 

 eventually find a place in this subfamily, but only those of which the status is 

 known are here included in it. A valve of Gemma is in the Museum labelled 

 as having been collected in Japan by Stimpson. I do not' feel confident of the 

 accuracy of this habitat and await further data before accepting it. 



/ Genus GEMMA Deshayes.^ 



Venus (sp.) Totten, Am. Journ. Sci., xxvi., p. 367, 1834. 



Cyrena (sp.) H. C. Lea, Am. Journ. Sci., xlii., p. 106, 1842. 



Venus (sp.) Gould, Inv. Mass., p. 88, 1841; Proc. Bost. Soc. N. Hist., p. 61, 1842; De 

 Kay, Zool. N. York, Moll., p. 218, 1843; Mighels, Boston Journ. Nat. Hist., iv., p. 321, 

 1843; Jay, Cat. Shells, ed. iv., Suppl., p. 466, 1852; Sowerby, Thes. Conch., ii., Venus, 



P- 737, 1853- 



Gemma Deshayes, Cat. Conch. Brit. Mus., i., p. 112, 1853; Venus gemma Totten; Stimp- 

 son, Checkl. N. E. Coast Shells, p. 3, 1860; Prime, Ann. Lye. Nat. Hist. N. Y., vii., p. 

 482 ; H. and A. Adams, Gen. Rec. Moll., ii., p. 419, 1857. 



Totteniana Perkins, Proc. Boston Soc. N. Hist., xiii., p. 148, 1869 (err. typ.). 



Tottenia Perkins, loc. cit. in errata. 



Gemma Tryon, Syst. Conch., iii., p. 180, 1884; Binney's Gould's Inv. Mass., p. 137, 1870; 

 Tryon, Am. Mar. Conch., p. 159, 1873 ; Verrill, Inv. An. Vineyard Sound, p. 683, 1873 ', 

 Dall, Bull. U. S. Nat. Mus. No. 37, p. 56, 1889; Journ. of Conch., Manchester, x., No. 

 8, p. 238, 1902. 



Shells small, subequilateral, rounded trigonal, with a rather large, faintly 

 circumscribed lunule, external ligament, and no escutcheon; sculpture of con- 

 centric waves or striation ; inner margins of the valves crenate ; pallial sinus 

 small, distinct, acute, free from the pallial line below; siphons separate, the | 

 branchial longer and papilliferous ; periostracum polished; hinge with three 

 cardinal teeth in each valve, an elongated posterior left and anterior right 

 lateral tooth received into a groove in the edge of the opposite valve ; foot 

 linguiform, not byssiferous. Type Venus gemma Totten. 



The genus is naturally a native of the east American coast from Maine to 

 Texas, but has been introduced with seed oysters at some points on the Pacific 

 coast. It is represented in the Tertiaries of the Atlantic and Gulf States. 



