250 VALLONIA. 



parent or slightly opaque, with a somewhat fatty gloss, smooth or 

 very finely and irregularly striate, smooth at the nucleus. Whorls 

 3-3 , rather rapidly increasing, with a moderately deep suture, the 

 last comparatively large, well rounded, expanding toward the apert- 

 ure, not descending in front. Aperture moderately oblique and 

 inclined, forming five-sixths of a circle, subangular at the base, the 

 umbilical margin somewhat protracted ; peristome everted only in the 

 inferior part, with a rather strong white lip, shining through the shell. 

 Alt. 1*1, greater diarn. 2'3, lesser 1*8 mill. 



Europe and eastern North America; Pyrenees; France; Lyons; 

 Germany ; Metz, Dresden and other places in Saxony ; Amtro-Hun- 

 gary ; Brosteni in the Carpathien Mts. ; Jura Mts. near Brugg in Swit- 

 zerland ; Washington, D. C. ; Staten Island, N. Y. ; Princeton, N. 

 J.; New Bedford, Mass. ; Saco and other places in Maine; Halifax, 

 N. S., Quebec, Canada ; New Philadelphia, Ohio. Everywhere 

 together with V. pulchella. 



Jaw moderately curved with a slight, wide median projection 

 on the cutting edge ; with rather fine dense, sharp, irregular ribs all 

 over. Radula with 81-84 transverse rows of 29 teeth ; 5 laterals ; 

 on the marginals the cusps are standing on a common sole, the inner 

 directed inward, the whole thus presenting a fan-like appearance. 



This shell is characteristic in its oblong outline, the last whorl 

 expanding at the aperture, the peristome not everted above and 

 only slightly below ; the comparatively small, little elevated spire, 

 and the suture which is not as deep as in V. pulchella. It also aver- 

 ages a little smaller than this. 



V. excentrica is variable only within narrow limits ; its size goes 

 very little above and below the average ; in many examples, or 

 forms, the outline of shell and umbilicus is less markedly elongate. 

 Some are also more glossy, transparent and shining than others. 

 Frequently the last whorl gradually ascends in front, as shown in 

 fig. 6, a feature often found also in other species, such as in pulchella, 

 costata and parvula ; and then the suture becomes deeper toward the 

 aperture. A striking feature in fresh examples, is the white lip 

 shining through the shell. 



It is surprising that this species has been overlooked, or rather 

 thrown together with V. pulchella, especially in Europe, where it 

 must be mixed with that species in numberless lots in collections, 

 and from which it is distinguished at first glance when once known. 

 In North America evidently Morse (I. c.) paid attention to it, 



