MICROrilYSA. 171 



Microphysa vortex, Tin. 

 Vol. III. ri. XLVIII. Fi^r. 2. 



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

 ent; whorls 5, proinincnt, with exceedingly mimite, ol)li((ue striae of inereasc ; 

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

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

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



Jlclix vortex., Pkeiffer, Arch. f. Nat. 1839, II. 351 ; Mon. Hftl. Viv., I. 95.— 

 Chemnitz, ed. 2, II. 110, PI. LXXXVIII. Figs. 7-9. — Ukkve, Con. Icon., 

 G44 (1852). — Gould, Terr. Moll., III. 34. —W. G. Binney, Terr. Moll., IV. 

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



lIcUx srlcnina, GouLD, Bost. Proc, III. 38 (1848); in Terr. Moll., II. 240, PI. 

 XXIX. a, Fig. 2 ; PI. XLVIU. Fig. 2. — Reeve, Con. Icon., 716 (1862). 



Ui/aliiia 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. 



Tills small species does not exceed Zonites arhoreus 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 difierent specimens. 



Jaw not observed. 



Lingual membrane (PI. HI. Fig. T) : 18—1—18 teeth, with 8 laterals. Tlie 

 sixteenth marginal tooth is shown. 



Microphysa Lansingi, Bland. 



ShelP imperforate, orbicular-depressed, shining, dark horn-colored, smooth 

 above, at the base substriate ; suture impressed ; whorls b\, 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 acutcf the right margin thickened within by an obsoletely denticulated 



1 T. imperforata, orbiculato-depressa, fusco-cornea, superne laevigata, basi substriatula; 

 sutura inipressa; anfr. 5^ convexiusculi, ultimusnon descendens, ad peripheriam obsolete 

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

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

 raellari vix reflexiusculo. 



