356 A MANUAL OF AMERICAN LAND SHELLS. 



inicrophysa vortex, Pfr. 



Shell iirabilicated, depressed, pale bluish-white, pearly, very thin, 



Fig. 384. transparent ; whorls 5, prominent, with exceedingly minute, 



I \ \, oblique strise of increase ; suture deeply impressed ; base 



\ZL- somewhat convex; axis open, umbilicus infuudibuliform ; 



aperture flattenedtransverse; peristome thin, acute, not 



reilected. Greater diameter G, lesser 5^™" ; height, 23"™. 



Helix vortex, Pfeiffer, Arch. f. Nat., 1839, ii, 351 ; Mon. Hel. Viv., i, 



M. vortex. 95. — Chemxitz, ed. 2, ii, 110, pi. Ixxxviii, figs. 7-9. — Reeve, Cou. 



Icon., 644 (1852).— Gould, Terr. Moll., iii, 34.— W. G. BIxVNEY. 



Terr. Moll., iv, 117; L. & Fr. W. Sli., i. 



Helix seUnina, Gould, Bost: Proc, ii, 38 (1848); iu Terr. Moll., 11,240, i)l. xxix, a, 



fig. 2; pi. xlviii, fig. 2.— Reeve, Con. Icon., 716(1862). 

 Hi/alimi vortex, Tryon, Am. Journ. Couch., ii, 252 (1866). 

 Microphysa vortex, W. G. Binney, Terr. Moll.,v, 171. 



Florida Sul)region ; Southern Florida and the adjacent islands, 

 Fig. ?s5. introduced from the West Indian fauna ; also west coast of 

 Florida. 

 The species is apparently viviparous. Fig. 385 represents 



Embryonic 



youii's of an embryonic shell taken from an adult by Mr. Morse. 



M. vortex, 



enlarged. rpj^jg gjQall spccics docs not excccd Zonites arhorens in size. 

 Its transparency 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 defined and deep. The aperture is trans- 

 verse and flattened in its vertical diameter; 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 sometimes 

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

 which is more or less prominent in different specimens. 

 Jaw of a specimen collected by Mr. H. Hemphill at Marco, on the 



Fig. 385 a. west coast of Florida, low, fig. 385 6. 



c^^ C^TlQrO slightly arcuate, with little 

 ^^^ / ^1 \)\ attenuated, blunt ends; trans- 

 parent, very thin, so as to 



Lingual dentition of lficro^%sa • i i 



vortex. curl ovcr on Us ends and mar- 



gins ; no median projection to lower margin ; about 

 30 widely separated, delicate ribs, serrating either 



, ,. i , • i' Ti 7 • 7 Jaw of Microphysa vor- 



margin; general appearance or the jaw ot Jbuiimulus. tex. 



Lingual membrane (Terr. Moll., Plate III, Fig T), lS-1-18 teeth, 



