ZONITES. 101 



Genitalia, as well as complete anatomy, fifrnrcd in Vol. T. PI. IX. Fig. 4. 

 Tliore is a peculiar plandiilar .striictin-c around the va^iiina. The; ])eni,s sac is 

 long and narrow, tapering aljove into tlu> vas deferens : the retractor muscle is 

 inserted at about its middle. The genital bladder is large, oval, on a long duct. 

 The peculiar accessories to the penis sac of capnodcs^ hcvigatus, inornatus, and 

 fridhilis are wanting. 



I have in my cabinet a large reversed specimen. 



Zonites friabilis, W. G. Binn. 



Shell very globose, transparent, brittle, thin, sometimes thick, shining, red- 

 dish; spire very short, conic; w^horls 5, convex, lightly wrinkled, rapidly 



increasing, the last very large and ventricose ; suture mod- 



^' . . Fig. 21. 



erate ; aperture circular, equally high and broad, within 



bluish and slightly thickened by a very thin white callus ; 



peristome simple, sharp, thin, at its junction with the 



body-whorl violet-colored and reflected, so as to cover a 



portion of the small and deep umbilicus ; the parietal wall 



of the aperture is covered with a light violet-colored callus. Zonites jriabiiis'. 



Greatest diameter 26, lesser 20 mill.; height, 13 miU. 



Rclix friabilis, W. G. Binney, Proc. Acad. Nat. Sci. Phila. 1857, 187; Terr. 



Moll., IV. 106, PI. LXXX. Fig. 2. — Pfeiffer, Men. Hel. Viv., IV. 346.— 



Bland, Ann. N. Y. Lye, VII. 126. 

 Eelix lucuhrata, Pfeiffer, Men. Hel. Viv., IV. 68 ; Mai. Blatt. 1858, 32, not 



of Say, VI. 132. 

 Hyaliiia friabilis, Tryon, Am. Joum. Conch., II. 247 (1866). 

 Zonites friabilis, W. G. Binney, L. & Fr.-W. Sh., I. 287, Fig. 514 (1869). 



The species belongs to the Interior Region, but reaches its greatest develop- 

 ment in the vicinity of Wabash County, Illinois. I have also received it from 

 Indiana, from the northern and northeastern counties of Kentucky, from Frank- 

 lin County, Tennessee ; in the southwesterly direction, however, its range is 

 greatest, as I have traced it to the Hot Springs of Arkansas, and to "Washing- 

 ton County, Texas. 



Animal bluish slate-color. The caudal pore, locomotive disk, and longitudi- 

 nal furrows above the edge of the foot are all present. 



Jaw as usual in the genus. 

 • Lingual membrane similar in type to that above described of Z. capnodes. 

 Teeth about 57—1—57, with 6 perfect laterals (PI. II. Fig. J). 



The genital system is figured on PI. XL Fig. D. The ovary is stout, light- 

 brown, and blunt. The oviduct is short. The vagina is long and narrow, with 

 a yellow prepuce-like expansion (pp) at the entrance of the duct of the geni- 

 tal bladder, which is near the base. Tlie genital bladder is large, oval, on a 

 duct of about equal length and size as the vagina. The penis sac is long and 



