18 



and in many other minor respects. The pallets are not unlike those of T. 

 dilatala, Stimpson, but the shell differs very much. 



I am much indebted to my valued correspondent, John H. Thomson, Esq., of 

 New Bedford, for over a hundred specimens of this species, and take great 

 pleasure in dedicating it to him as a slight recognition of the services which 

 he has rendered to most of the Conchologists of the United States. 



In a recent letter, referring to this species, he writes, " I am sorry to say 

 that their name is legion, even the Cedar buoys in the Harbor only last one 

 season. 



Teredo navalis, Linn. Accompanying the above were a few valves and 

 tubes of this species. 



Xylotrya fimbriata, Jeffreys. I also found among the New Bedford Teredss, 

 two pallets, apparently belonging to this species. 



Xylotrya stocea,Tryon. Mr. Gabb writes to me that this Californian species, 

 which I supposed was quite rare, when I described it, is committing great 

 ravages in the harbor of San Francisco, and is unfortunately very numerous 

 in individuals. 



Descriptions of two new species of Mexican Land Shells. 

 BY GEORGE W. TRYON, JR. 



HELIX RisuoNDi, Tryon, t. 2, f. 1. 



Description. Shell narrowly umbilicated, thin, turbinately globose. Epi- 

 dermis very thin, light corneus, with a single narrow chestnut band encir- 

 cling the periphery and visible just above the sutures of the spire. Substance of 

 shell thin and appearing smooth to the naked eye, but under a lens minutely 

 punctate. Whorls four, slightly convex, the last rounded, scarcely descending. 

 Base of the shell convex, but with a narrow angle around the umbilicus. 

 Aperture rotundately semi-lunar ; lip slightly expanded and reflected ; the 

 margins not approaching on the columella, which is entirely free from 

 callus. 



Dimensions. Diam. maj. 17. min, 15, alt, 12 mill. 



Habitat. Cinaloa, near Mazatlan. Auguste R6mond. 



Observations. This pretty species resembles, in some respects, H. Trypan- 

 omphala Pfr. from "Sierra Maestra, Mexico," but evidently differs somewhat in 

 form, and particularly in that of the lip. 



I name it after our Corresponding Member, M. Auguste Remond, of the 

 Calfornia Survey, who collected it and kindly sent it to me for description. 

 The two specimens before me are almost precisely alike in form and size. 



Helix ventrosula, Pfr. Near Mazatlan ; M. Remond. Not previously reported 

 from the West Coast of Mexico. 



Glandina turris, Pfr. Near Mazatlan, M. Remond. 



CYCLOTUS COOPERI, Tryon, t. 2, f. 2. 



Description. Shell widely umbilicate, globosely turbinate, rather thick, 

 covered with a corneous epidermis, unmarked except by crowded and rather 

 deeply cut growth lines. Spire conoidal, more or less depressed. Whorls 

 4JJ to 5, convex. Lip simple, straight, acute; the junction of the margins 

 scarcely angulated, and merely touching the body of the shell above. 

 Aperture white and shining within. Operculum ? 



Dimensions. Diam. maj. 16, min. 14, alt. 12 mill. Long, apert. 1 mill. 



Habitat. Cinaloa, near Mazatlan. Auguste Remond. 



Observations. This species is not unlike C. translucidum, Sby., in form, 

 but has a wider umbilicus, is much thicker in texture, and the growth lines 

 are strongly impressed. 



Named after Dr. J. G. Cooper, Zoologist of the California State Geological 

 Survey. 



