2 THE NAUTILUS. 



the Proc. Cal. Acad. Sciences (Series 2, Vol. V, p. 36), he makes the 

 following remarks concerning my " Tres Marias, etc.," list : " Out 

 of 294 in the catalogue, about 200 occur in the Gulf and several 

 others on the west coast. It is not, therefore, as complete a list of 

 Gulf shells as we might expect from collections made by the U. S. 

 Fish Commission Steamer 'Albatross,' with its facilities for dredg- 

 ing and collecting otherwise." As my paper does not purport to be 

 a list of the "Albatross " collections in the regions under considera- 

 tion, but only includes incidentally such species as were collected by 

 the "Albatross " naturalists at a few points only, viz., " Baelenas 

 and Pichelinque Bays, etc., so far as the same have been worked up 

 at this date," as is distinctly stated, further comment is unnecessary. 



Los Angeles, Cal., April 5, 1897. 



ON A NEW FORM OF POLYGYRA FROM NEW MEXICO. 



BY W. H. BALL. 



Polygyra rhyssa Dall, n. sp. 



Shell of six rounded whorls, dark yellowish-brown, the suture 

 rather deep and the spire low but not flattened ; nuclear whorls 

 nearly smooth, the rest of the shell rather coarsely obliquely stri- 

 ated, the last fourth of the last whorl with rather sharp elevated 

 riblets with wider interspaces and a marked constriction behind the 

 reflected peristome ; umbilicus small, deep ; periphery above the 

 middle of the whorl rounded, the entire surface more or less dis- 

 tinctly finely spirally striate; aperture subcircular, oblique, with a 

 reflected and rather solid peristome with a small obscure thicken- 

 ing on its basal part, a light wash of callus over the body, and 

 slightly within the aperture a small oblique elongated parietal den- 

 ticle. Major diameter 17, minor diameter 14; height 9 mm. 



White Mountains of New Mexico, Ashmun. 



This species is about the size of P. chiricahuana Dall, from which 

 it differs by its strong sculpture, somewhat larger umbilicus, more 

 distinct suture and oral armature. The form of the mouth resem- 

 bles that of P. pseudodonta Dall, but the basal thickening of the lip 

 is not notched and the shell is decidedly larger, more coarsely sculp- 

 tured and somewhat darker in color. It forms another illustration 

 of the effect of insulation on the mountain peaks by arid lowlands 



