TRIODOPSIS. 



309 



FiK. 202. 



taolcs ; lenpjth of cyc-pcdimclcs al^out a (quarter of an inch ; foot nan'ow, equal 

 in lenfijth to nearly twice the diameter of the shell, terminating in an acute 

 anixle (sec B. J. N. II., I. PI. XVII.). 



Jaw as usual ; over 10 ribs. 



The lingual membrane (PI. VII. Fig. M) lias 2.')— 1—25 

 teeth ; 1 laterals. The inner cutting point is bifid after the 

 tenth tooth. 



Genitalia (PI. XV. Fig. D). The penis sac is long, cylindri- 

 cal, receiving the vas deferens and retractor muscle at its sum- 

 mit ; genital bladder small, globular, with a long duct, which is narrow above, 

 but below its middle gradually enlarges to greater than the width of the 

 bladder. The details of the size of the genital bladder and its duct seem to 

 offer an excellent specific character to the members of this group of I'riodopsis 



T. tridentala, 

 (leformcd. 



Fie. 203. 



Triodopsis Harfordiana, J. G. Cooper. 



Shell umbilicated, depressed-globose, thin, surface scarcely broken by incre- 

 mental wrinkles, horn-colored; spire slightly elevated, apex obtuse; whorls 4, 

 convex, suture impressed, the last globose below ; aperture 

 oblique, lunate, trilobed, one tooth on the parietal wall, and two 

 on the reflected peristome ; peristome white, broad, reflected, with 

 a toothlikc process near either termination. Greater diameter 

 9, lesser 6 mill. ; height, 3 mill. 



Helix Harfordiana, J. G. Cooper, Amer. Joum. Conch., V. 196, 

 PI. XVII. Fig. 3 (1870). 



In the Californian province, in Fresno County, " Big Trees," 

 latitude 37°, 6,500 feet altitude. In the Central Province at Sal- 

 mon River, Idaho. 



Jaw as usual ; ribs over 1 2. 



Lingual membrane (PI. VII. Fig. R,) as usual in the genus. Teeth 26 — 1 — 26, 

 with 1 2 laterals. The side cutting points to central and lateral teeth are well 

 developed. 



Triodopsis fallax, Say. 

 Vol. III. PI. XXVIII. 



Shell umbilicated, depressed-globose, with rib-like striae, reddish horn-colored; 

 spire convex ; whorls 6, rather convex, the last deflected anteriorly, constricted; 

 aperture trilobed, contracted by a large, oblique, tongue-shaped, arcuately en- 

 tering tooth on the parietal wall ; peristome reflected, thickened within, white, 

 with 2 teeth, the upper one bending inward not on the edge, the other sub- 

 basal. Greater diameter 13, lesser 11 mill.; height, 7^ milL 



Helix fallax, Say, Journ. Phila. Acad., V. 119 (1825) ; Binney's ed., 27. —De- 

 Kay, N. Y. Moll., 28, PI. III. Fig. 23 (1813). — Pfeiffer, Men. Hel. Viv., I. 



