1893.] NATURAL SCIENCES OF PHILADELPHIA. 255 



Europe, being taken for pulchella. In North America we meet the 

 old question of the validity of V. (Hel.) mimita Say. When Say 

 described this species, "he was probably unacquainted wiikVallonia 

 pulchella of Europe, as he makes no remarks on the resemblance of 

 this species to the European form," as Morse (I.e.) justly 

 remarks, continuing: "Stimpson, Kirtland, and De Kay retain the 

 specific name of minuta for this shell, while Binney, Gould, W. G. 

 Binney, Adams, Mighels and all the European writers unite it with 

 pulchella." 



Among writers since Morse's publication, opinion is still divided. 

 Say's description (I. c.) is as follows : " Shell rather thick ; spire con- 

 vex, little elevated, with three volutions ; suture well-defined, 

 impressed ; whorls obtusely wrinkled across ; aperture nearly orbi- 

 cular; lip much thickened, reflected, white, distant from the umbili- 

 cus ; umbilicus large, exhibiting the volutions. Breadth less than 

 one-tenth of an inch." The description decidedly points to pulchella 

 in nearly every particular and can not be applied to exeentrica. 

 Say, himself, ■ however, later acknowledged the identity of his 

 minuta with pulchella, 19 and these are reasons enough for not apply- 

 ing this name to a species distinct from pulchella. 



Morse (I. c.) expresses the opinion that the American shell, 

 minuta, is distinct from the European, pulchella, and proves it, 

 mainly from the shape of the aperture and the angle formed by the 

 latter with the axis of the shell, the American form being more 

 translucent, and the epiconch somewhat different. 



J. W. Thomson 20 refers only to V. minuta, and adds : " I cannot 

 consider this species to equal H. pulchella Mull." It certainly is prob- 

 able that Morse had ourF. exeentrica before him, as it, as well as pul- 

 chella, is frequent in Maine, but it is surprising that he did not 

 speak of other differences, especially the peculiar shape of the 

 umbilicus, the outline of the whole shell, and the fact that the peris- 

 tome is very little everted in comparison with pulchella. The trans- 

 parency of the shell differs in each species, and I have seen exeen- 

 trica rather more opaque than usual in pulchella. The form of the 

 upper part of the aperture is also variable in pulchella as well as in 

 exeentrica, especially in the suture slightly descending to the aper- 

 ture in many specimens, while in others it does not. The difference 

 in the inclination of the aperture I have not found so constant and 



19 See W. G. Binney, Terr Moll. IV, p. 69. 



20 The Land Mollusca of Bristol Co., Mass., Journ. Conch., 1S85, p. 372. 



