256 PROCEEDINGS OF THE ACADEMY OF [1893. 



marked after comparing numerous specimens from many localities 

 on both continents. 



Morse also speaks of differences in the lingual dentition and buc- 

 cal plate (jaw) between minuta and pulehella, but it seems not from 

 his own observations ; and it must be said that his description and 

 figure 21 of the radula seem rather to be drawn from pulehella than 

 from what we consider excentrica. The latter has the formula 14- 

 1-14, or 29 in a transverse row against 23-1-23 in pulehella. I 

 would have drawn the marginals (or uncini, as he calls them) differ- 

 ently, had he then really had excentrica before him. Since the two 

 species live together along the Atlantic coast, it is probable that 

 they were mixed, as is the case in nearly every lot coming from the 

 coast from Maryland to Nova Scotia. The mistake was very likely 

 to occur, even in the case of such a careful observer as Morse. 



W. G. Binney, 22 as well as other writers, is of the opinion that 

 there is only one species, pulehella, and his own description as well 

 as figures represent the same. Evidently he examined only exam- 

 ples of the species referred to. 



Has V. excentrica been introduced from Europe ? It is found only 

 in the East, in the oldest settled parts of the country, where also 

 several European Limaces are common. But the latter live almost 

 exclusively in and about dwellings, while Vallonia seems to be 

 spread all over the region. Thus it may be considered native here 

 as well as V. pulehella and costata. 



3. V. adela Westerlund. 



Hel. adela Westerlund, Ofversigt af K. Vet. Ak. Forh., 1881, 4, p. 37. ' . 

 Hel. adela Westerlund, Fauna der in der Palaearktischen Region lebenden 

 Binnenconchylien, J, Berlin, 1889, \>. 14. 



" Shell openly umbilicated, depressed trochiform or convex, very 

 indistinctly, finely striate or smooth, whitish ; whorls 4-4*, rather 

 convex, not at all angular at the rather deep suture, rather rapidly 

 increasing, the last comparatively large, rounded, not expanded, 

 not descending in front ; aperture crescentic-circular, with mar- 

 gins separated, peristome very narrowly everted or almost straight 

 and without a lip. Size 21 to 3 : li to If mm. (Suabian Alps ; fossil 

 in a sub-marine peat-bog, near Ystad, in southern Sweden.") 



The above description is translated from West. Fauna, I. c. I 

 have seen no specimens. Two examples, in a vial, with the label : 



21 L. c.,p. 21, fig. 57, PI. 8. 



22 L. c. and Invertebrata of Mass. ed. II, p. 428. The outlines of the upper fig- 

 ure in the latter rather strongly resemble those of V. costata; generally the 

 umbilicus is not as regular as shown in the lower figures of either work. 



