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Mollusca of Middlebury, Vt. and Vicinity. Q71 
__ Deshayes remarks,.(Liam. An. sans, Vert. 2nd edit.,) in common 
with some others, it establishes a passage between the two gen- 
era, and proves the uselessness of one of them. 
FJ e « 
Popa. . 
P. armifera, Say. Of this species, not before known this side 
the Alleghany Mountains, (Gould, Monog. Bost. Journ. Nat. Hist. 
Vol. III, p. 401,) Ihave found a very few specimens in Bridport 
on the borders of Lake Champlain, and Prof. Benedict has found 
it at Crown Point. : 
P. badia, nob. This species was discovered in company with 
the preceding by Prof. Benedict. Dr. Gould (op. cit.) remarks 
that it is “almost precisely like” P. marginata, Drap. That 
species has a narrower aperture and wider umbilicus. It is quite 
possible however that a comparison of numerous specimens may 
establish their specific identity. 
P. albilabris, Ward’s letter. 'This species is well known as 
Say’s Cyclostoma marginata. 'The late lamented Dr. Ward, of 
Roscoe, Ohio, ascertained that it was a Pupa, and, as Say’s spe- 
cific name had been pre-occupied in this genus, proposed for it the 
hame which we have given. A few specimens only in this re- 
gion have been found by Prof. Benedict. 
P. ovata—syn. Vertigo ovata, Say. This species has been 
mistaken by some for P. modesta, Say, but a specimen with all 
the teeth fully developed leaves no doubt in my view of the cor- 
rectness of others, who have regarded it as P. ovata. It is rare 
in this vicinity, but is more common near Boston. 
. contracta, Say. 'This species is found quite plentifully. 
Mature specimens vary considerably in size. 
P. exigua, Say. This very neat little species is rather common. 
P. milium, Gould. This is the most minute shell, which has 
been described in this country. Twelve mature specimens to- 
gether weighed less than .06 gr., or .005 gr. each. The Delphi- 
nula serpuloides, nob., the least of the marine shells of New Eng- 
land, weighs precisely twice as much. The dimensions of Pupa 
milium are, length .06 in., breadth .03 in. The Heliz pygmea, 
Drap., ‘Gcconling to Paton. (Land and Fresh Water Shells of 
Great Britain,) is 05 i in. broad, and Deshayes ss (op. cit.) 
that it is “une des plus petites espéces connues.” This Pupa 
therefore is probably the most minute of known ‘batt with the 
exception of the microscopic Cephalopods. 
