DESCRIPTION OF A NEW SPECIES OF HYALINA. 



BY WM. II. DALL. 



Dr. V. Sterki, of New Philadelphia, Ohio, lias of late years been giv- 

 ing special attention to the minute forms of Pulmonata, Vertigo, Pupilla, 

 Hyaliitd, etc. In 1880 he collected a small Zonites, of the section 

 Hyalina or Conulus, which, being submitted to several 

 naturalists, appeared to be a new species, although of 

 remarkably small size. In 1887 a few more specimens 

 were obtained, which he has submitted to me with the 

 request that I describe them. 



H. testa parva, convexiusculo depressa, nitida, striis 

 incrementalibusiucouspicuis; suturavixitnpressa, anfr. 

 iv, rotundati, ultimas circa umbilicus imperforatus ex- 

 cavatus; apertura depressa, vixobliqua, ampla, lunaris; 

 perist. simplex, acutum, margine dextro columellari vix 

 reflexiusculo. Diam. maj., l.l mm .; alt, 0.52 mm . 



Shell minute, thin, yellowish translucent, brilliant, 

 lines of growth hardly noticeable, spire depressed, four- 

 whoiied; whorls rounded, base flattened, somewhat ex- 

 cavated about the center, which is imperforate ; aper- 

 ture wide, hardly oblique, not very high, semiluuate, 

 sharp edged, the upper part of the columella slightly 

 reflected; upper surface of the whorls roundish, though the spire as a 

 whole is depressed. Max. diameter 0.044 inch (line A — b, Fig. 1) ; alt. 

 0.02G inch. 



This little shell is clearly not the young of a Pupilla or of any of our 

 other small Zonites. It is certainly the smallest American species. H, 

 parvula Rong, from Cape Verde Islands, has a little less diameter, but 

 is higher in the spire. II. pygmcea and R. minutissima Lea are decidedly 

 larger, beside belonging to a differeut group. It is probably one of the 

 smallest species known, and remarkable for its imperforate umbilicus. 

 It was collected on a grassy slope, inclining to the northward, and 

 covered with grass, moss, and small bushes, aud so far fras not been found 

 anywhere else. Its permanent place in the system wdl, of course, be 

 determined by an examination of the soft parts, which remains to be 

 made. 



Proceedings U. S. National Museum, vol. xi, 1888. 

 214 



FlGB. 1 to 3. Hya- 

 lina stcrkii, n. s. 



