MICROPHYSA. 171 



Microphysa vortex, PFR. 

 Vol. HI. PI. XL VIII. Fig. 2. 



Shell umbilicated, depressed, pale bluish-white, pearly, very thin, transpar- 

 ent; whorls 5, prominent, with exceedingly minute, oblique striae of increase; 

 suture deeply impressed ; base somewhat convex ; axis open, umbilicus infun- 

 dibuliform ; aperture flattened-transverse ; peristome thin, acute, not reflected. 

 Greater diameter 6, lesser 5j mill. ; height, 2| mill. 



Helix vortex, PFEIFFER, Arch. f. Xat. 1839, II. 351 ; Mon. Hel. Viv., I. 95.- 

 CHEMNITZ, ed. 2, II. 110, PI. LXXXVIII. Figs. 7-9. REEVE, Con. Icon., 

 644(1852). GOULD, Terr. Moll., III. 34. W. G. BINNEY, Terr. Moll., IV. 

 117; L. & Fr.-W. Sh., I. 



Helix selenina, GOULD, Bost. Proc., III. 38 (1848) ; in Terr. Moll., II. 240, PI. 

 XXIX.. a, Fig. 2 ; PI. XLVII1. Fig. 2. REEVE, Con. Icon., 716 (1862). 



Hyalina vortex, TRYON, Am. Journ. Conch., II. 252 (1866). 



Florida Subregion ; Southern Florida and the adjacent islands, introduced 

 from the West-Indian fauna. 



The species is apparently viviparous, Fig. 116 of Land and Fresh- Water 

 Shells, I., representing an embryonic shell taken from an adult by Mr. Morse. 



This small species does not exceed Zonites arboreus in size. Its transpar- 

 ency is greater than that of any other of our species. The general character 

 of its upper surface is that of depression ; but though the whorls revolve in 

 nearly the same plane, the suture is so deeply impressed that each whorl is 

 rendered convex or tumid. The umbilicus is of small diameter, but well de- 

 fined and deep. The aperture is transverse, and flattened in its vertical diam- 

 eter ; the peristome is thin, sharp, and not turned outwards. The convexity of 

 the base being greater than that of the upper surface, an obtuse angle is some- 

 times produced on the periphery of the shell at the line of their junction, which 

 is more or less prominent in different specimens. 



Jaw not observed. 



Lingual membrane (PI. III. Fig. T) : 18 118 teeth, with 8 laterals. The 

 sixteenth marginal tooth is shown. 



Microphysa Lansingi, BLAND. 



Shell 1 im perforate, orbicular-depressed, shining, dark horn-colored, smooth 

 above, at the base substriate ; suture impressed ; whorls 5^, rather convex, the 

 last not descending, obsoletely angular at the periphery, more convex at the 

 base, excavated around the umbilical region ; aperture narrow, lunate ; peri- 

 stome acute, the right margin thickened within by an obsoletely denticulated 



1 T. imperforata, orbiculato-dcpressa, fusco-cornea, superne Isevigata, basi substriatula ; 

 sutura unpressa; anfr. 5A convexiusc.uli, ultimus non desceudens, ad peripheriam obsolete 

 angulatus, subtua convexior, circa regionem umbilicarem excavatus; apertura anguste 

 lunaris; peristomate acuto, margine dextro lamella obsolete serrata iutus incrassato, colu- 

 mellari vix rcllcxiusculo. 



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