32 PHYSA GYRINA. 



of the labium to grow over extraneous matter, 

 and the want of a fold in the columella. "Its 

 motions are exceedingly rapid; very timid, with- 

 drawing itself on the least alarm." 



PHYSA GYRINA, Say. 



Plate 3.— Figs. 1—6. 



P. testa elongata, castanea vel rubra: anfractibus 5 — 6 

 convexis: sutura impressa: apice acuto: apertura ovato- 

 elongata; plica columellari obsoleta. 



SYNONYMS AND REFERENCES. 



Physa GYRINA, Say. Jour. Acad. Nat. Sci., v. ii. p. 171. 

 F. ELLiPTicA, Lea. Tr. Am. Phil. Soc. n. s., vol. v. p. 

 115, pi. xix. fig. 83. 



DESCRIPTION. 



Shell oblong, polished, and translucent, with 

 five or six convex whirls, and a well marked 

 suture: spire gradually tapering to an acute 

 apex: aperture more than one half the entire 

 length, frequently thickened within the margin: 

 columellar fold obsolete. 



