MUSEUM OF COMPARATIVE ZOOLOGY. 



195 



Zonites caducus, Pfeiffer. 



cerinoideus, Anthont. 

 Gundlachi, Pfeiffek. 

 Found also in Texas, at Hidalgo, by Dr. Singley. 



Zonites Singleyanus, Pilsbky. 



Shell minute, broadly umbilicate, planorboid, the spire scarcely perceptibly ex- 

 serted; subtranslucent, waxen white, shining, smooth, under a strong lens seen to 

 be slightly wrinkled by growth-lines; whorls three, rather rap- 

 idly increasing, separated by well impressed sutures, convex, the 

 apex rather large; body whorl depressed, slightly descending, 

 indented below around the umbilicus ; aperture small, semilunar, 

 oblique; peristome simple, acute. Umbilicus nearly one third 

 the diameter of the shell, wide, showing all the whorls. 



Alt. 1, diam. 2 mm. 



New Braunfels, Comal Co., Texas. 



Allied to Z. minusculus, but much more depressed, more shin- 

 ing, smoother, smaller, with broader umbilicus and a complete 

 whorl less than minusculus. 



This species, one of the most distinct of the smaller forms of 

 Hyalina, was communicated to me by Mr. J. A. Singley, in whose Zonite e n ^r|ed yanUS ' 

 honor it is named. I have also found a few specimens among the 

 shells collected by myself in Central Texas, during the winter of 1885-86. With 

 Z. Singleyanus at New Braunfels are found quantities of Z. minusculus. The latter 

 species exhibits some variation, being often more depressed than more northern 

 specimens. This depressed form has been noticed in Mexico by Strebel, who pro- 

 poses for Z. minusculus the new generic title of Chanomphalus, which is, of course, 

 completely synonymous with Pseudohyalina, Morse, 1864, and this, again, is not dif- 

 ferent enough from Hyalina to warrant the erection of a new genus or subgenus. 

 There is some variation in the width of the umbilicus in Texan specimens of Z. mi- 

 nusculus, but I have not seen specimens with it so wide as Dr. Dall indicates for 

 his var. Alachuana from Florida. H. elegantulus, Pfr., is about the size and form of 

 my Zonites Singleyanus, but it is a strongly sculptured species. 



The above description was published by Pilsbry, Proc. Phil. Acad., N. S., 

 1889, p. 84, Plate XVII. Figs. 6, 7, 8. A specimen kindly furnished me by 

 Dr. Singley for the purpose is drawn in my figure. 



Zonites Dallianus, Simpson. 



Shell minute, depressed, narrowly umbilicated, fragile, pale straw- 

 colored, somewhat shining ; under a lens seen to be marked with 

 delicate growth-lines above, smoother beneath. Spire a little con- 

 vex ; apex subacute ; sutures scarcely impressed. Whorls three 

 and one half, scarcely convex, the last wide. Aperture oblong- 

 lunate, oblique, upper and lower margins sub-parallel, slightly con- 

 verging; peristome acute. Alt. 1J, diam. maj. 3, min. 2\ mm. 



West Florida, at Shaw's Point, Manatee Co., and Little Sarasota 

 Ray. 



Zonites 

 Dallianus, 

 enlarged. 



