11 



15. Sph. triangulare, Say. 



Cyclas triangularis, Say, New Harm. Dissem. 356, 1829. 



Animal not observed. Shell transversely oval, nearly equilateral, rather 

 full, anterior margin slightly distended, rounded, posterior somewhat abrupt, 

 nasal rounded ; beaks large, full, prominent ; lines of growth regular, epi- 

 dermis brownish ; hinge margin narrow, curved ; cardinal teeth very distinct, 

 assuming the shape of the letter V reversed ; lateral teeth prominent. 



Long. 9-16 ; lat. 7-16 ; diarn. 4-16 inches. 



Hab. N. America, in Mexico. (Cabinet Acad. Nat. Sci. Philada.) 



The specimens from which I have prepared this description were presented 

 to the Academy of Natural Sciences of Philadelphia by Mrs. Say, as the Cyclas 

 triangularis, Say ; they may or may not be true representatives of Say's 

 species. In many points they answer his description of the C. triangularis, 

 but at the same time I am not able to reconcile their shape, which is not more 

 triangular than that of any other species, with the name he has applied to 

 the species. Moreover, they bear a very strong resemblance to one of out- 

 Northern Sphserium, the Sph. solidulum; they differ from it, however, in 

 being less heavily and more regularly striated, and in having more prominent 

 beaks. 



b. Species with protuberant or calyculate beaks. 



16. Sph. elevatum, Hald. 



Cyclas devata, Hald., Acad. Nat. Sci. Phila., Proc., i. 53, 1841. 

 C. pallida, DeCharp., MSS. 1851. 



Animal not observed. Shell ovate, orbicular, nearly spherical, cavity 

 large, equilateral, margins well rounded ; beaks 

 central, slightly inclined towards tlie anterior, lap- 

 ping over the outline of the shell, large, tumid, 

 approximate, calyculate, prominent ; hinge margin 

 slightly curved ; cardinal teeth united, prominent ; 

 lateral ones elongated ; large, valves very strong, 

 interior bluish ; surface smooth, striation light, 

 irregular ; color brownish olive, greatly varied by 

 zones of a lighter shade, a zone of bright yellow 

 bordering thelnferior and part of the lateral margins. 

 Long. 9-16 ; lat. 8-16 ; diam. 5-16 inches. 



Hab. N. America, at New Orleans, La., and in Florida and Alabama. 

 (Cabinets Acad. Nat. Sci. Philada., and Prime.) 



Remarkable for its transversely spherical shape, which renders it distinct 

 from all other species of this genus. It is much more solid than the generality 

 of calyculate species, the valves being as strong as those of any of the larger 

 species of the preceding group. 



The Cyclas pallida, the young of this species, is more delicate than the 

 adult ; it is a little less transversely spherical, the striae are lighter, and the 

 color is bright yellow. 



Prof. Haldeman's original specimen of the Cyclas e 1 e v a t a , from which 

 this description was prepared, and which is now in the cabinet of the 

 Academy of Natural Sciences, though very perfect in appearance, comprised 

 but a single valve. 



This species seems to be very rare. I have never met with any other 

 specimens but the one in the cabinet of the Academy and those I have in 

 mine, two specimens of the Cyclas pallida, derived from De Charpentier 

 himself, and a single valve from Florida. 



17. Sph. partumium, Say. 



Cyclas partumia, Say, Acad. Nat. Sci. Phila., II. 2, 380, 1822. 



C. cornea, var. 2, Lam., An. s. vert. v. 558, 1818. 



C 1 . orbicularia, Barrat, Amer. II. xlviii. 276, 1845. 



C. mirabilis, Prime, Bost. Proc. iv. 157, 1851. 



C. ccerulea " loc. sub. cit. iv. 161, 1851. 



C. eburuea, Anthony, " " " iv. 279, 1852. 



