MAZATLAN UNIVALVES 



Subgenus STBOMBINA. 



sis 



To which, group of ColumbellidEe these shells are most allied, 

 has not yet been determined. They are ranked provisionally 

 imder Anachis. 



657. Steombina maculosa, Sow. 



ColumbeUa maculosa, Sotc. in Proc. Zool. Soc. 1832, p. 115 : — 

 Thes. Conch, p. 139, no. 84, pi. 40, f. 152.— Desk, in Lam. 

 An. s. Vert. vol. x. p. 291, no, m.—Chenu, Conch. HI. pi. 12, 

 f. 7, 8, 



Strombina maculosa, S. & A. Ad. Gen. i. 186. 



This shell is like an elongated A. coronata, being similarly 

 painted, and having the upper whirls smooth, and the lower 

 ones tuberculated. The second row of tubercles is scarcely 

 indicated in the smaller (adult) specimen, while the larger one 

 is entirely destitute of them. Base spirally striated. The 

 largest sp. measures long. 1'02, long. spir. 'G, lat. '32, div. 26°. 



Sab. — Guacomayo, in sandy mud, Cuming. — Mazatlan ; 2 dead 

 specimens ; X/'pool Col. 



Tablet 2436 contains the smaller (more perfect) specimen. 



658. ? Steombina , sp. hid. 



Tablet 2437 contains a young shell, very elongate, with 3 

 smooth nuclear Avhirls ; also a fragment of an adult ; surface 

 with deep u-regular pits, formed by the confluence of spiral 

 and radiating ridges. 



SaJj. — Mazatlan ; extremely rare, off Spondj'lus ; L'pool Col. 



Genus PISANIA, Biv. 



Bivon. Nuov. Gen. 1832, p. 13 -.—Phil. Handh. Conch, p. 149, 

 no. 21 : — H. ^ A. Ad. Gen. vol. i. p. 83.=-Pusio, Gray. 



+ Ponia, Gray, Zool. Beech. Voy. 1839, p. Ill -.—Phil. loc. cit. 

 p. 148, no. 20 :— =Cantharus (Bolt.) H. Sf A. Ad. Gen. vol. i. 

 p. 84. 



