MAZATLAN BIVALVES 61 



89. DOSINIA ANNJE, n. s. 



D.t. co mp ressd, elongatiore, marginibus aqualiter 

 arcuatis : sulcis concentricis subdistantibus, haud i mp res- 

 sis, medio subobsoletis ; lunuld oblongd, subimpressd; lacted, 

 epidermide flavescente, medio tenuissimd ; dentibus hand valde 

 diver gentibus : sinu pallii haud magno, angulato, apice ad 

 m arginem ventralem 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 to the middle, in this towards the ventral edge 

 of the anterior adductor. Long. 2*44, lat. 2*35, alt. 1*12. 

 Hob. Mazatlan ; very rare ; L'pool Col. 



Tablet 258 contains a young and a full grown specimen. 



A- 90. DOSINIA DUNKERI, Phil. 



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



pi. 2, f. 9. (Oct. 1844.) 

 Artemis Dunkeri, Rve. Conch. Ic. pi. 6, f. 34. Ad. fy Rve. Voy. 



Samarang, p. 78, pi. 21, f. 17. Soiv. Thes. Conch, p. 657, 



no. 7, pi. 140, f. 5. C. J9. Ad. Pan. Shells, p. 274, no. 448. 

 Dosinia Dunkeri, Desk. JB. M. Cat. Ven. p. 8, no. 9. 

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



Descr. Cat. Ap. pi. 19, f. 41. Eve. Conch. Ic. pi. 10, f. 9. 



Sow. Thes. Conch, p. 657, no. 8, pi. 140, f. 6. (Dosinia s.) 



Desk. B. M. Cat. Ven. p. 9, no. 11. 

 Cytherea Pacifica, (Mus. Berol.) Trosch. in Wiegm. Archiv. 



p. 324, (non Dillw.) 



After very patient but altogether ineffectual attempts to 

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

 many hundred specimens which have passed under review, I 

 am imformed by Mr. Hanley himself that his species is the 

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

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

 known 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 striae, 

 Sept. 1855. g 



