1889.] NATURAL SCIENCES OF PHILADELPHIA. 83 



Of course the miscellaneous collection of small Helices under 

 Mierophysa in Albers-Marten's Die Heliceen should be to some ex- 

 tent dismembered (although most of them are probably true 

 Microphysae), as well as the genus as constituted by Biuney (Terr. 

 Moll, v.), and only the species agreeing in characters of shell and 

 dentition with H. booth iana, H. vortex, H. inerustata etc. be included. 

 This group then, after the elimination of all snails with narrow, 

 thorn-shaped marginal teeth, will comprise about twenty species of 

 West Indian shells. Its relations are probably with Patula. The 

 jaw so far as I know is ribbed ; but this is a character of secondary 

 importance. Mierophysa has nothing to do with the minuscuhis 

 group of small Zonites. It belongs to a different family. 



Zonites dallianus Simpson. PI. III. figs. 9, 10, 11. 



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 converging ; 

 peristome acute. 



Alt. H, diam. maj. 3, min. 2|> mill. 



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

 Bay. 



Differs from Z. arboreus Say in the smaller spire and wider last 

 whorl ; fewer whorls ; differently shaped aperture. It is about half 

 the size of Z. arboreus, and the sculpture is the same as in that 

 species. The Helix ottonis of Pfeifier, of which specimens from 

 Cuba and Havti are before me, has no special relationship to this 

 species, but is undoubtedly a synonym of Z. arboreus, as Pfeiffer him- 

 self concluded. H. ottonis differs from arboreus in nothing but the 

 lighter color ; the form and dimensions are precisely as in arboreus. 

 (See Pfr. in Wiegm. Archiv fur Naturgesehi elite, 1840, p. 251 ; the 

 species was never described in the " Monographia Heliceorum.") 



The aperture in Z. dallianus is less lunate than in Z. arboreus, 

 emb racing less of the penultimate whorl ; seen from beneath, the 

 greater portion of the aperture lies outside of the periphery of the 

 penultimate whorl; whilst in Z. arboreus the reverse is the case. 

 The much smaller size of dallianus also separates it from Z. arboreus. 



This species was sent me under the above name by Mr. Chas. T. 

 Simpson, the well-known student of Floridan shells. The same 



