Dall.] 256 [March 16, 



Liocyma Dall, n. g. (Aelos, smooth, and xd/j.a, wave.) Shell 

 trigonal or elongate-ovate, small, thin, smooth; furnished with con- 

 centric undulations and occasionally fine radiating lines; provided 

 with a polished epidermis; pallial sinus small, rounded triangular; 

 hinge teeth three in each valve, divaricate ; middle tooth largest, 

 grooved on the upper edge. Lunule faint, no areola, ligament set in 

 below the exterior surface. Soft parts : — siphons equal, short, pro- 

 vided with numerous cylindrical papillae around the apertures, no 

 valve in either siphon, both closely united, to their tips. Branchial ; 

 inner layer extending from the posterior to the anterior adductor, 

 broadly triangular, pointed behind ; outer layer short, spatulate, nar- 

 row and close to the post adductor; mantle smooth, united around 

 the siphons and before the foot, with an opening nearly as long as the 

 shell for the passage of the foot; the latter is elongate-rhomboidal, 

 with the edges sharply compressed, anterior extremity pointed, lan- 

 ceolate. Palpi four; upper pair slender, narrow, pointed, smooth; 

 lower pair stouter, dextrally spiral, with two turns. Type, Venus 

 fluctuosa Gould, Inv. Mass., 1841, p. 47, pi. iii, fig. 50. Binney, Inv. 

 Mass., 2d ed., p. 136, fig. 447 (young). 



The type of this genus was referred to Venus and Tapes by Gould, 

 to Chione and Tapes by Deshayes, and finally to Anaitis by Roemer. 

 The latter name is preoccupied in Lepidoptera as well as Botany, 

 and must therefore be dropped. This species, moreover, does not 

 agree with the types of Roemer 's genus. Dr. Gould's original figure 

 and description refer to one of two species which appear to have 

 been confounded under the same name. They may be characterized 

 as follows : — 



Liocyma fluctuosa Dall ex Gould. 



Venus fluctuosa Gld., Inv., 1841, p. 87, pi. iii, fig. 50. Otia Conch., 

 p. 181. Stm., Sh. of N. E., p. 19. Binn., Inv., 2d ed., p. 136, 

 fig. 447 ( jun.). De Kay, Nat. Hist. N. Y., p. 220. 



Venus astartoides Beck, Midd. Mai. Ros. , in, p. 56. Sib. Reise, 

 Moll., p. 252, pi. xx, figs. 5-14. Philippi, Abb. u. Beschr., in Bd., 

 p. 61, t. ix, fig. 4. Sowerby, jun., Thes. n, 737, pi. cxxxviii, fig. 

 157. 



Tapes fluctuosa Gld., Otia, p. 181. Deshayes, B. M. Cat. Biv., p. 

 176, n. 47. H. & A. Ad., Gen. Rec. Moll., n, p. 435 (not of Sow- 

 erby). 



Chione astartoides Desh., (!) B. M. Cat. Biv., p. 147. 



Chamelea astartoides H. & A. Ad., (!) Gen. Rec. Moll., II, p. 423. 



