TRIODOPSIS. 303 



Helix denotata, Fi^^RUSSAC, Tab. Syst., 38 (1822), no dcscr. ; TTist., V\. XL. a, Fig. 



5 ; ri. L. a, Fig. 7. — Desiiayes in Lam., VIIL 115 ; ed. 3, IIL 309. 

 Helix votata, Desiiayes, Encyd. Meth., IL 224 (1830). 

 Xolotrema palliaUi, TiiYoN, Am. Journ. Conch., IIL 49 (1867). 



A post-Pleiocene species, now found in the Northern and Interior Regions ; 

 from Canada to Georgia, and Louisiana. 



Animal of a uniform, blackish slate-color over the whole upper surface ; foot 

 narrow, in length double the diameter of the shell, and terminating in an acute 

 point ; eye-peduncles one third of an inch long ; eyes not distinguishable from 

 the general color (see p. 301). 



The nature of the epidermis and sculpturing are the only constant specific 

 characters which distinguish palUata from ohstricta. In the former the epider- 

 mis has " numerous minute tuberculous acute prominences " ; the striae are close 

 together, and somewhat irregular in development. In the typical form the 

 whorls are convex, with a well-impressed suture ; the last whorl is obtusely an- 

 gulated in front of, but not behind the aperture. 



The species varies in the form of the whorls and extent of the angulation of 

 the periphery, as follows : — 



Var. /3. — Whorls flattened above, slightly exserted, the last more sharply 

 angulated in front of the aperture, with the striae, especially behind the aper- 

 ture, more distinctly defined. Greater diameter 22, lesser 19^ mill.; height, 

 8^ mill. (5 whorls.) Kentucky and Tennessee. 



Var. y. — Whorls planulate above, and so exserted as to show the carinated 

 edges of all excepting the apicial whorls, the last whorl with an acute project- 

 ing carina continued to the back of the aperture ; the umbilicus not always 

 entirely covered by the reflected lip. Greater diameter 21^, lesser 18| mill.; 

 height, 7 mill. (5 whorls.) Tennessee. 



The lingual membrane (PI. VII. Fig. O) has 34 — 1—34 teeth; 12 perfect 

 laterals; another specimen had 14 laterals. Morse counted 115 roAvs of teeth. 

 The inner cutting point of the transition teeth in this species is very large, as 

 shown in c. 



Jaw as usual, with more than 15 ribs. 



Genitalia figured by Leidy, 1. c. The genital bladder is very elongate-ovate, 

 on a duct of about equal length, swelling to equal size as it approaches the 

 vagina; the penis sac is short, cylindrical, with a constriction at its upper part, 

 beyond which it tapers slightly, and receives the vas deferens at its apex ; the 

 retractor muscle is inserted in the vas deferens near its junction with the penis 

 sac ; the vas deferens near the prostate gland is swollen into a small bulb-like 

 expansion ; the same is seen in 2\ ohstricta, 



Triodopsis obstricta, Say. 

 Vol. m. PI. XV. 



Shell with the umbilicus closed, depressed, with heavy, rib-like striae, and in- 

 terstitial, minute, revolving lines, reddish horn-color ; spire flattened ; whorls 5, 



