ZONITES. 101 



Genitalia, as well as complete anatomy, figured in Vol. I. PI. IX. Fig. 4. 

 There is a peculiar glandular structure around the vagina. The penis sac is 

 long and narrow, tapering ahove into the 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 cajmodes, la'vigatus, inoraatus, and 

 friabilis 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; whorls 5, convex, lightly wrinkled, rapidly 



increasing, the last very lanre and ventricose; suture mod- „. „„ 



. . . . r»g- 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 Jriabilis'. 



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



Helix friabilis, W. G. BlNNEY, Proc. Acad. Nat. Sci. Phila. 1857, 187; Terr. 



Moll., IV. 106, PL LXXX. Fig. 2. — Pfeiffer, Mon. Hel. Viv., IV. 346.— 



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

 Helix lucubrata, Pfeiffer, Mon. Hel. Viv., IV. 68 ; Mai. Blatt. 1858, 32, not 



of Say, VI. 132. 

 Hyalina friabilis, Tryon, Am. Journ. Conch., II. 247 (1866). 

 Zonites friabilis, W. G. BlNNEY, L. k 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 (PL II. Fig. J). 



The genital system is ngu. .:d on PL XL Fig. D. The ovary is stout, light- 

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

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

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

 duct of about eii'tai length and size as the vagina. The penis sac is long and 



