286 



A MANI'AL OF AMERICAN LAND SHELLS. 



Fig. 304. 



T. palliata. 



Fir,. 305. 



T. obstricta. 



Jaw as usual, with more tbau 15 ribs. 



Geuitalia figured by Leidy, I. c. The gcDital 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 ujjper part, beyond 

 which it tapers slightly and receives the vas deferens at 

 its apex ; the retractor muscle is inserted in the vas de- 

 ferens near its junction with the penis sac; the vas de- 

 ferens near the prostate gland is swollen into a small bulb- 

 like expansion ; the same is seen in T. obstricta. 



A curious individual of the species is figured here, in which the peri- 

 stome is carried around the umbilicus instead of over it. 



Triodopsis obstricta, Say. 



Shell with the umbilicus closed, depressed, with heavy, rib-like 

 striae and interstitial, minute, revolving lines, reddish 

 horn-color; spire flattened; whorls 5, depressed, the 

 last convex below, with a prominent, acute carina 

 above; aperture oblique, subtriangular, narrowed by a 

 tongue-shaped, arcuately entering tooth on the parietal 

 wall ; peristome thin, broadly expanded, its inner edge with a heavy 

 thickening of white callus, its right portion with a stout, erect denticle, 

 its basal portion straight, dilated, reflected, with a long, lamellar, less 

 prominent denticle. Greater diameter 26, lesser 22°^™ ; height, 11">". 



Melix obstricta, Say, Jonrn. Pbila. Aca(l.,ii, 154 (1821); Binney's ed., 17.— Pfriffer, 

 Mou. Hel. Viv., i, 317.— Eeeve, Con. Icon., No. 683 (1852).— W. G. Binxey, 

 Terr. Moll., iv, 57; L. & Fr.-W. Sh., i, 125 (1869).- Bland, Ann. N. Y. Lye, 

 vii, 446. 



Helix palliata, var. a, Say, Journ. Pbila. Acad., ii, 152; Binney's ed., 16.— Var. a,b, 

 De Kay,N. Y. Moll., 33, yl. ii, fig. 16.(1843).- Var., Binney, Terr. Moll., ii. 

 137, pi. XV. 



Helix appressa, var., Desha yes, in Feh. (in plate, not in text). 



Helicodonta denotata, var., Ferussac, Tab. Syst., 38 ; Hist., pi. 1, a, fig. 7, no dcscr. 



CaracoUa helieoides, Lea, Trans. Am. Pbil. Soc, iv, 103. pi. xv, fig. 34; Obs., i, 113 

 (1834). 



Helix Caroliniensis, Lea, Trans. Am. Pbil. Soc, iv, 108, i>l. xv, fig. 33 ; Obs., i, 112(1834). 



Xolotrema o&s//k'^«, TuYOX, Am. Jonru. Coucb., iii,49 (1867). 



Triodopsis obstricta, W. G. Binney, Terr. Moll., v, 303. 



A Post-Pliocene species (Natchez Bluit), now found in the Interior 

 Eegion, in Ohio, Indiana, Tennessee, Georgia, South Carolina. 



T. obstricta differs from T. ixdliata in the following particulars : The 

 epidermis is free from "tuberculous i)romineuces," but has raised spiral 

 lines between the costiii, on the upper and lower surfaces of the shell. 

 It has elevated, rigid, distant costa^,, the whorls are subexserted and 



