1893.] NATURAL SCIENCES OF PHILADELPHIA. 247 



Hel. pulchella var. laevigata Moq.-Tand., 1855, a. o. 

 Hel. minuta Say, Journ. Acad. Phila., 1S17, p. 123. 

 IIi'l. minuta Say, Nichols. Enc, ed. 3, 1819. 



Vallonia minuta Morse, Pulmonifera of Maine, 1S64, p. 21 (part). 

 Vallonia minuta Tryon, Am. Journ. Conch., Ill, 1867, p. 36 (?). 

 Vallonia pulchella W. G. Binney, Terr. Moll. V., p. 344. 

 Vallonia pulchella W. G. Binney, Man. Am. Land Shells, 1885, p. 77. 



Shell of medium size, first moderately, then for the last \ whorl 

 widely umbilicated, convex or depressed conic above, pale horn or 

 straw colored, transparent or milky opaque, fiuely and densely 

 striate, somewhat stronger and rather regularly at the suture and 

 the umbilicus, shining, smooth at the nucleus ; 13 whorls 33-4, rather 

 rapidly increasing, with a rather deep suture, the last comparatively 

 large, well rounded, little expanded toward the aperture, not de- 

 scending in front or slightly so at the suture ; aperture moderately 

 oblique and inclined, % circular with umbilical margin a little 

 more straight and slightly protracted ; peristome decidedly and 

 rather abruptly everted, with a strong, white lip, thinner at either 

 end. 



Diam. maj. 2-4, min. 2*0, alt. 1*2 mm. w 



Soft parts as described above for the genus. The liver was found 

 quite various in color: light yellow to lighter or darker brown, as 

 has been noted above. The action of the heart also is described in 

 the general description. 



The jaw (PI. VIII, figs. H, I, K, L) is rather strongly curved 

 with obtuse ends, and no median projection on the cutting edge. 

 The latter is more or less denticulated, irregularly, corresponding 

 with the 18-25 variously coarse, rather sharp, longitudinal ribs 

 irregularly distributed over the front plane of the jaw. For details 

 see general description, p. 235. The width of the jaw was found to be 

 0-13-0-23, the height 0-065-0-07 mm. 



The radula (PI. VIII, figs. A, G) has 65-70 transverse rows of 

 27 teeth ; it has already been said that Morse and "W. G. Binney 

 counted 23 and 21. There are three perfect laterals, with rather strong 

 mesodonts, rapidly diminishing in size from the first to the third. 

 The fourth and fifth make the transition, and at least the former is 

 different from the true laterals only by the longer mesodont of the 

 peculiar formation described above. In the fifth, which still has a 

 well-formed though smaller plate, the mesodont is of the same char- 



13 Yet, in a single specimen, I have seen few indistinct short lines. 

 u The altitude given here, and for all the following species, is of the whole 

 shell, since it is almost impossible to reliably measure in any other way. 



