256 VALLONIA. 



lots from China and Shanghai, China, of 3, and 2 specimens respect- 

 ively, one of each was the same as the tenera from Japan, while the 

 others were a trifle smaller, with a narrower umbilicus widened at 

 the opening, somewhat more elevated spire and of a more yellowish 

 horn color. The form is represented in pi. 33, fig. 53. It is possible, 

 consequently, that they represent a var. pulchellula Hde., but for 

 want of sufficient material, decision is better deferred. 



V. GRACILICOSTA Reinhard. PI. 33, figs. 48, 49. 



Shell flat, with little prominent apex, widely umbilicated, whitish- 

 gray in color. Whorls 3, convex, separated by a deep suture, with 

 fine but distinct, rather crowded ribs ; the last whorl slightly 

 angular around the umbilicus, strongly expanding toward the aper- 

 ture, slightly descending to the same. Aperture moderately oblique, 

 transversely oval, with strongly everted and broadly white-lipped 

 peristome ; upper margin but little, lower margin more curved, 

 almost obtusely angular. Margins at the insertions approximating 

 and connected by a callus. Alt. ca. *1, greater diam. 2*5, lesser 2'0 

 mill. (Original description, translated.) 



On the Little Missouri river collected by MM. Krause. 



F gracilicosta REINH., Sitzungsber. Naturf. Freunde Berlin, 1883, 

 p. 42. 



I have seen no authentic examples of this species, but think four 

 specimens from Logan Canyon, Utah, may range under it, and also a 

 few other examples from Quebec, Canada, which I observed living and 

 examined jaw and radula. In all of them, and also in the fossils to 

 be mentioned below, the last whorl ascends slightly and gradually 

 but distinctly, before it descends to the aperture. They are some- 

 what larger than given in the description. Greater diam. 2'6-2'8 

 mill. The ribs of the shell itself are rather strong, sharp and 

 crowded, (about 55 on the last whorl), but regular, with small, fine 

 membranous appendages. 



The jaw is large, of a pale horn color, thin, with rather crowded; 

 strong, irregular rib-striae. The radula is also comparatively large, 

 each transverse row with 33-35 teeth, and 6 laterals, on which the 

 cusps, and especially the ectodonts are larger than in F costata. 

 As to the shell, this species stands doubtless near costata; yet it 

 shows relations to those of the following group, in the formation of 

 the aperture, the ascending and descending of the last whorl and the 

 fine, crowded ribs. 



