1893.] NATURAL SCIENCES OF PHILADELPHIA. 265 



conch. Two examples, in the same condition, from "Winnipeg, 

 Manitoba, are related to these, but are somewhat smaller, and 

 resemble V. costata. V. albula, therefore, seems to be widely dis- 

 tributed over the northern part of our Continent, and more speci- 

 mens will probably be found in that region. 



7. V. parvula, n. sp., 2 5 PI. VIII, fig. R. Man. Conch.. PI. 32, figs. 23-26, 28. 



Shell small, widely umbilicated, especially for the last i-£ whorl, 

 quite flat above or with very little prominent apex, thin, horn- 

 colored to nearly colorless, with rather fine, dense, membranous 

 ribs (about 30-38 on the last whorl), and microscopic, intercrossing 

 lines between them; nucleus with fine revolving lines; whorls a lit- 

 tle over 3, slightly flattened above and below the periphery, with a 

 deep suture : the last much wider than the penultimate, rather rap- 

 idly expanding toward the aperture and descending only at the 

 suture in front ; aperture very oblique, tangential and rather 

 inclined, almost circular with ends of margin much approximate; 

 peristome with a rather strong, pale horn colored lip. Diam. maj. 

 2*0, min. 1*6, alt. about 0"8 mm. 



I was enabled to examine the soft parts through the kindness of 

 Mr. Jas. H. Ferriss. 26 The jaw is rather strongly curved, of about 

 the same configuration as that of V. costata (PL VIII, fig. N), stout,, 

 of chestnut color, with about 18 strong, coarse ribs, strongly denticu- 

 lating the cutting edge. They are of the formation described 

 above (PL VIII, fig. R). The side ends show hardly a trace of 

 ribs and appear smooth. 



I counted about 67 transverse rows of 23 teeth on the radula. There 

 are 3 perfect laterals, and the fourth may well range with them, being 

 very little modified by a somewhat small plate of attachment, the meso- 

 dont being nearly normal and the ectodont still simple but two- 

 pointed in most teeth. The fifth is formed like the marginals, but 

 the 2-3 distal cusps are very small and short. Thus the transition 

 is more rapid here than in any other species. There are 4 well- 

 formed marginals, with 4-5 comparatively short cusps ; the tenth 

 tooth bears hardly any perceptible cusps, and the eleventh (last) 

 not a trace of such. PL VIII, fig. P, shows a central tooth in half 

 profile with the strong and cusp-like prominent posterior angles of 



25 See notice in Nautilus, V, No. 3, p. 100. 



26 Who, upon my request to send living specimens, not finding any at Joliet. 

 made a trip of 8 miles in the worst of weather to secure them. 



18 



