MAZATLAN BIVALVES 61 



89. DosiNiA Ann^, n. s. 



D. t. compressd, elong atiore , marginihus cequaliter 

 arcuatis : sidcls concentricis suhcUstantihus, li aud i mp res- 

 sis, medio suhohsoletis ; lunula ohlongd, suhimpressd ; lacted, 

 epidermide jiavescente, medio tenuissimd ; dentibus haiul valde 

 divergentibus : si7iu pallii haud magno, angulaio, apice ad 

 m arginem ventral em muse, adduct. ascendente . 



This fine , and (for a Dosinia) well marked species is known 

 from D. ponderosa by its greatly elongated form ; from D. 

 Dunkeri by its larger size, flatter growth, smoother ribs (the 

 difference being at once perceived by drawing the nail along 

 the two shells) which are obsolete in the middle ; and especially 

 by the shape of the pallial sinus, which in D. Dunkeri almost 

 always points t ) the middle, in this towards the ventral edge 

 of the anterior adductor. Long. 2' M, led. 2' 35, alt. 1*12. 



JIab. — Mazatlan ; very rare ; L'pool Col. 



Tablet 258 contains a young and a full grown specimen. 



90. Dosinia Dunkeri, Phil. 



Cytherea Dunkeri, Phil. Abbild. Conch. Cyth. p. 4. no. 5, 



*pl. 2, f. 9. (Oct. 1844.) 

 Artemis Dunkeri, Rve. Conch. Ic. pi. 6, f. 34. — Ad. Sf Eve. Voy. 



Samarang, p. 78, pi. 21, f. n.—Soio. TJies. Conch, p. 657, 



no. 7, pi. 140, f. b.— C. B. Ad. Pan. Shells, p. 274, no. 448. 

 Dosinia Dunkeri, Desh. B. 31. Cat. Ten. p. 8, no. 9. 

 = Artemis simplex, Hani. Proc. Zool. Sac. Jan. 1845, p. 11 : 



Descr. Cat. Ap. pi. 19, f. il.—Bve. Conch. Ic. pi. 10, f. 9.— 



Sow. Thes. Conch, p. 657, no. 8, pi. 14^), f. 6.— (Dosinia s.) 



Besh. B. M. Cat. Yen. p. 9, no. 11. 

 Cytherea Pacifica, (Mies. Berol.J Trosch. in Wiegm. Archiv. 



'p. 324, (non DiUw.) 



After very patient but altogether ineifectual attempts to 

 separate D. simplex of the monographs from D. Dunkeri, in the 

 many hundred specimens which have passed under review, I 

 am iiiiformed by Mr. Hauley himself that his species is the 

 same as Phdippi's ; and as the name of the latter bears date a 

 few months earlier, it is necessary to preserve it. The shell is 

 kno-wn by its very rounded, inflated form, more or less produced 

 ventrally ; the more produced form is the D. simplex of the 

 monographs. It varies somewhat in the closeness of the strise, 



Sept. 1855. g 



