FREE INSTITUTE OF SCIENCE 



TERTIARY FAUNA OF FLORIDA 



think correctly, the other being a dementia already discussed in this memoir 

 (see p. 1235). 



In M. maculata the pallial sinus is ample and rises more from the hori- 

 zontal than in the species previously mentioned, but not as high as in the 

 Parisian forms. It is variable in acuteness, some specimens having the an- 

 terior part pointed, others linguiform, and still others rather blunt, as if 

 obliquely truncated. 



Callista cuneata Gabb, 1881, from the Pliocene clays of Costa Rica, is evi- 

 dently congeneric, and differs, according to Gabb, from M. maculata by its 

 straight instead of convex posterior slope. 



Cytherca Horidana Conrad, 1846, appears to belong hereabouts, but I have 

 seen no specimens from Ballast Point which agree with Conrad's figure in the 

 American Journal of Science (p. 400) and his description is quite insufficient. 



Genus AMT.ANTIS Carpenter. 

 Amiantis Carpenter, Suppl. Rep. Brit. Assoc. for 1863, pp. 526, 640, 1864 (Cytherea callosa 



Conr.) ; Ann. Mag. N. Hist., xv., p. 178, 1865; Romer, Mon. Venus, i., p. 140, 1868; 



Tryon, Syst. Conch., iii., p. 178, 1884; Fischer, Man. de Conchyl., p. 1079, 1887. 

 Afnyantis Stoliczka, Cret. Pel. India, p. 151, 1871. 



Shell large, solid, ovate, concentrically waved, with vernicose periostracum ; 

 lunule and a linear escutcheon defined by an impressed line ; inner margins 

 smooth; pallial sinus ample, acute in front, free below, slightly ascending; 

 three cardinals in each valve, the anterior one very thin, anterior laterals large 

 and strong. Type Cytherea callosa Conrad, 1838 (-\-Dione nobilis Reeve, 

 1849). 



Section Amiantis s. s. 



Shell, except when abnormally thickened, with two obscure radial ribs 

 internally near the middle of the disk ; posterior cardinals elongated, strong, 

 the right one bifid ; the other teeth entire ; the posterior left cardinal and the 

 edge of the right nymph rugose ; the posterior dorsal^nargin beyond the hinge- 

 plate grooved to receive the edge of the opposite valve. 



Section Encallista Dall, 1902. 



Shell with tl< . posterior cardinals snort ; the opposite faces of the nymphs 

 with intf; rugosities, the teeth smooth, the interior without radial 



ridges. rypt Cytherea purpitra^ Lamarck; Reeve, Conch. Icon. Dione, pi. 

 viii., fig/32, 186?. 



