1904.] NATURAL SCIENCES OF PHILADELPHIA. 421 



Zonitoides minusculus Binn. 



Locality 807, and recent. Its abundance in the one deposit and 

 absence in the others is a Httle surprising. 

 Zonitoides bristoli n. sp. PI. XXXVI, fig. 13. 



Shell resembling Zonitoides minusculus in general form, but much 

 smaller, only moderately umbilicate, white, costulate, and densely 

 sculptured with spiral lines ; composed of 3 convex whorls. Apex 

 somewhat elevated. Aperture lunate, the outer and basal margin 

 more imiformly curved than in Zonitoides minusculus, and the preced- 

 ing whorl cutting out a greater arc. Peristome simple, thin. Costulse 

 regularly spaced, coinciding with growth lines. The spaces between 

 them crowded with fine striae. A close, regular, spiral sculpturing 

 crosses these lines and gives the costulse a slightly tubercular appear- 

 ance. 



Alt. .7 Diam. 1.17 mm. 



Named in honor of Dr. C. L. Bristol, of New York University, Associate 

 Director of the Bermuda Biological Station for Research. 



One specimen from each of localities 807 and 818; the type from the 

 latter place. 



Succinea bermudensis Pfr. 



I S. bermudensis Pfr., P. Z. S., 1857, p. 110; Monographia, IV, p. 817. 

 S. barbadensis Pilsbry, Trans. Conn. Acad., X, p. 502. 



Localities 807, 806, 818, 80S, 809 and recent. In the absence of alco- 

 hohc specimens of S. barbadensis I have given up that name and re- 

 turned provisionally to the name bermudensis. Its presence as a fossil 

 makes it not unlikely that it may be proved distinct from S. barbadensis. 

 This is another species that was formerly larger than now. The largest 

 fossil, from locahty 808, measures alt. 13, diam. 7 mm. The largest 

 out of 30 recent specimens lent by Mr. Bryant has alt. 12, diam. 6.3 mm. 

 Helicina convexa Pfr. 



If this species were indigenous we could expect it to be as abundant 

 formerly as it is now. Instead of that it seems to be entirely absent 

 from the beds I examined. The evidence seems to me strong that its 

 real home is elsewhere. 



