252 PROCEEDINGS OF THE ACADEMY OF [1893. 



2. V. excentrica n. sp., PL VIII, fig. B, M. Man. Conch., PI. 32, figs. 6-9. 

 Vallonia minuta Say, Morse, Pulnionif. Me., p. 21 (part.). 



Shell of medium size, with maj. diam. markedly longer, and with 

 irregular, somewhat elongated umbilicus at first rather narrow, then 

 for the last & whorl rapidly widening ; slightly rounded convex 

 above, smooth or vex*y finely and irregularly striate, strongly and 

 regularly at the umbilicus ; nucleus smooth ; jDale horn colored, 

 transparent or slightly opaque, with a somewhat fatty gloss; whorls 

 3—3 J , rather rapidly increasing with a moderately deep suture, the 

 last comparatively large, well rounded, expanding near the aper- 

 ture, not descending, or very little at the suture; aperture moder- 

 ately oblique and inclined, I circular, subangular at the base; the 

 umbilical margin somewhat protracted ; peristome not everted 

 above, very little at the periphery and moderately below, with a 

 rather strong white lip, thinner at the ends, visible through the 

 shell. . 



Diam. maj. 2 - 3, min. T8, alt. 1*1 mm. 



I was enabled to see the soft parts in a few specimens from Que- 

 bec, kindly forwarded by Mr. H. W. Hanham. The foot is, com- 

 pared with that of costata, a little less transparent and of a slight 

 yellowish tinge, as is also that of pulchella. But this difference of 

 tint is perceptible only when the animals are side by side. The Jaw 

 (Pi. VIII, fig. M) is moderately curved above ; the cutting edge 

 with a slight, wide median projection and almost straight side 

 parts ; the ends are rounded. The front bears rather fine, dense, 

 sharp, slightly irregular ribs, all over. Size of jaw 0*08 mm. high, 

 0'28 wide, when depressed. 



The radula (PI. VIII, fig. B) has 81-84 transverse rows of 29 

 teeth. There are four perfect laterals ; the fifth marks the transi- 

 tion ; it distinctly shows the peculiar formation of the mesodont, 

 has smaller though well-formed plate of attachment, and two small 

 distal cusps, the ectodont being already split. The sixth is a mar- 

 ginal but still marks the transition : it is triangular, with 3-4 cusps. 

 With the exception of the last 1 or 2 which are hardly serrate, the 

 marginals are pectinate with 5-7 cusps, and the 7tb— 10th are 

 placed in a peculiar way, as at least the 3-4 mesial cusps are stand- 

 ing on a common socle. The radula is 0*79 mm. long., 0*29 wide; 

 one transverse row measures, as usual, nearly 0"01 mm. 



The animal seems to be somewhat less lively and more timid than 

 V. costata. 



