1896.] NATURAL SCIENCES OF PHILADELPHIA. 451 



shells are nearly covered, leads to the suspicion that it is composed 

 of the execreta of the animal itself, as it is laid on in little sausage- 

 like or subcylindrical masses and attached by a dry substance, re- 

 calling the silvery streaks left by crawling slugs. 



Leptinaria chathamensis Dall. Plate XVI, fig. 9; Plate XVII, fig. 16. 



Leptinaria chathamensis Dall, Nautilus, V, p. 98, 1892 ; Stearns, Proc U. S. 

 Nat. Mus., xvi, pp. 418, 428, 1893. 



BiiHmulus {Felecostoma) cymatoferiis Reibisch, Isis, 1892, pt. 3, p. 14, t. ii, 

 fig. 7. 



Chatham Island, on ferns 1,600-2,000 feet above the sea, Dr, 

 Baur ; also on dry bones of tortoises. South Albemarle Island, Baur. 



Shell small, horn-colored, with a blunt apex and six rounded 

 whorls ; suture very distinct, surface polished, delicately marked 

 with lines of growth ; base rounded, relatively rather widely umbil- 

 icated ; aperture with the margin hardly thickened, rounded in 

 front and at the suture ; pillar broad, thin ; body with a single ele- 

 vated, thin, sharp lamina, extending spirally inward from a point a 

 little behind the peristome and nearly equidistant from the inner 

 and outer lips^ alt. of shell 3.0, max. diani. 1.6 mm. 



Analogous forms are found in the mountains of the Panamic 

 resrion and on several of the Pacific Islands. As all the American 

 species are believed to belong to Leptinaria, as distinguished from 

 Tornatellina, I have no hesitation in referring this species to the 

 American type. The radula of this form is extremely minute and 

 difficult to find when boiled out in liquor potassse. I sacrificed sev- 

 eral specimens without success, and the tooth figured is from a 

 sketch by Mr. Binney. His slide has deteriorated so much in keep- 

 ing that I have been unable to find the radula upon it after long 

 scrutiny. 

 Helicina (Idesa) nesiotica Dall. Plate XV, figs. 1, 2 ; Plate XVII, fig. 12. 



Helicma {Idesa) nesiotica Dall, Nautilus, V, p. 97, Jan., 1892; Stearns, Proc. 

 U. S. Nat. Mus., xvi, p. 418, 1893. 



Helicina Wolfi Keibisch, Isis, 1892, pt. 3, p. 17, t. ii, fig. 13; Stearns, Proc. 

 U. S, Nat. Mus., xvi, p. 416, 1893. 



On the leaves of plants 1,600 feet in elevation, near the S.-W. end 

 of Chatham Island, Dr. Baur ; Albemarle Island, Reibisch in Hit. 



Shell small, depressed, with rounded periphery, base moderately 

 convex, and peristome not thickened nor reflected ; epidermis of a 

 bright reddish chestnut, polished, but with obvious regular incre- 

 mental lines ; base with a thin white callus merging into the lower 

 lip without notch or angle ; spire depresssd, suture very distinct. 



