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TERTIARY FAUNA OF FLORIDA 



or indicating resting stages, when they may cross the disk ; hinge very heavy 

 and well developed ; basal margins faintly crenulate ; pallial sinus small, dis- 

 tinct. Length 4.25, height 4.0, diameter 2.6 mm. 



This species is nearly as common as G. magna but much smaller and much 

 heavier than G. magna of the same size, from which it is further distinguished 

 by its smooth surface. 



Gemma gemma Totten. 



Pl.\te 24, Figures i, 3. 



Venus gemma Totten, Am. JoUrn. Sci., ist Ser., xxvi., p. 367, pi. L, fig. 2, 1834 ; Russell, 

 Essex Journ., i., p. 58, 1839; Gould, Inv. Mass., p. 88, fig. 51, 1841 ; Proc. Boston Soc. 

 N. Hist., i., p. 61, 1842 ; Mighels, Boston Journ. N. Hist., iv., p. 321, 1843 ; Stimpson, 

 Shells of N. Engl., p. 19, 1851 ; Sowerby, Thes. Conch., ii., p. 737, ph clviii., fig. 141, 



1853- 

 Gemma gemma Deshayes, Cat. Conch. Brit. Mas., i., p. 113, 1853; H. and A. Adams, Gen. 



Rec. Moll., ii., p. 419, pi. cvii., fig. 3, 1857. 

 tVenus manhattanensis Prime, Jay's Cat., 4th ed., Suppl., p. 466, 1852 ; Ann. Lye. Nat. 



Hist. N. Y., vii., p. 482, 1862. 

 Gemma Totteni Stimpson, Checkl. East Coast Shells, p. 3, i860; Prime, loc. cit., p. 483, 



1862. 

 Tottenia gemma Perkins, Proc. Boston Soc. N. Hist., xiii., p. 148, 1869 (see errata) ; 



Verrill, Invert. An. Vineyard Sd., p. 682, pi. xxx., fig. 220, 1873. 

 ■^ Gemma purpurea Dall, Bull. U. S. Nat. Mus. No. 37, p. 56, No. 283, 1889. 

 Gemma purpurea var. Totteni Dall, Trans. Wagner Inst., iii., p. 919, pi. xxiv., figs, i, 3, 



1898. 

 Gemma gemma subsp. Totteni Dall, Jour. Conch. (Manchester), x.. No. 8, p. 241, 



1902. 



Pleistocene of Massachusetts Bay at Point Shirley, Stimpson ; living from 

 Labrador south to Long Island Sound and New York Bay, Prime. 



This form is more ovate than either of the Tertiary species and more ovate 

 and compressed than the variety purpurea H. C. Lea, which, were it not for a 

 certain number of intermediate forms, would be regarded as distinct. The 

 external sculpture is somewhat irregular, the spaces between the concentric 

 sulci varying in width, while the sulci themselves are sometimes very fine and 

 close-set. In well-developed specimens of the southern form the sculpture is 

 relatively strong and regular. Both vary in color. Specimens identified by 

 several of the older naturalists with Venus manhattanensis seem to me to be 

 merely pale or white specimens of the present form. 



