SPH^RIUM. 103 



as having them, such as are named under the synonymes ; but they 

 are probably all of them varieties of this species. The young, dif- 

 fering widely as it does from the adult, has been commonly received 

 in our cabinets as Say's C. rhomboidea. A specimen one fourth of 

 an inch long would answer very well to his description. What the 

 true rhomboidea is, I have not yet been able to satisfy myself. The 

 two species of Lamarck, also, I believe to be varieties of this shell ; 

 and very probably his C. striatina also. 



[Mr. Prime, by an examination of specimens in the Jardin des 

 Plantes, has come to the conclusion, no doul)t correctly, that this 

 is certainly C. sulcata of Lamarck, and has given that as the prior 

 name. He seems not to have seen the first edition of Nicholson's 

 Encyclopiedia, in which Say gave his description, which bears date 

 two years earlier (1816).* C. Sarratog-ea, however, represents the 

 adult shell, according to Dclessert's figures, and C. sulcata and 

 striatina, yomig forms. 



Spliserivim partumeium. 



Fig. 54. 



Shell rounded-oval, snb-equipartite, lowest anteriorly, somewhat angular be- 

 hind ; thin and frag-ile ; valves very convex, minutely wrinkled by lines of growth, 

 and obsoletely radiated ; light horn-color ; beaks elevated. 



Ci/clas partumeta, Say, .Joiirn. Acad. Nat Sc. ii. .380 (1822). — Ferussac, Mag. de Zool. 



18.3.T. — T)e Kay, Nat. Hist. New York, 22.3, pi. 2.5, fig. 262. — Stimpson, Shells of 



New England, 16. — Prime, Proc. Bost. Soc. Nat. Hist. iv. le-i, 278. — Mighels, 



Shells of Maine, 12, in Journ. Bost. Soc. Nat. Hist. iv. 318. 

 Cyclas cornea, var. 2, Lam. An. sans Vert. vi. 268 (1835). — C. B. Adams, in Thoinp. 



Venn. 168. — Gould, Inv. 1st ed. 73 ; Catal. 30. 

 Cyclas cccrulea, Prime, Proc. Bost. Soc. iv. 161 (1852). 

 Cyclas viirahilis. Prime, ibid. iv. 167 (1852). 

 S/ihceriuin ccFruleum and mtrahi/e. Prime, Adams's Gen. ii. 450. 

 SpluEriitin partumeium, Prime, Pr. Ac. Nat. Sc. xi. 296 (186U). 

 Sphcerium partumium, Prime, Op. cit. xii. 29. 



See Prime's Synonymy of Cyclades, in Proc. Acad, of Sciences, xi. 296. 



Shell rounded-oval, highest behind, thin, fragile, pellucid, some- 

 what inflated ; Ijeaks nearly central, moderately elcA-ated, inclining 

 inwards ; hinge-margin nearly straight, passing by a regular curve 

 into the rounded anterior extremity, but curving suddenly behind, 



* Dr. Gould is incorrect in regard to the date. The second volume of tlie first edition, 

 containing Mr. Say's article Conchology, bears the date of 1817. The only public library 

 which to my knowledge contains this edition is that of the U. S. Naval Academy at An- 

 napolis. — W. G. B. 



