TRIODOPSIS. 305 



membrane which has the cutting points of its teeth quite blunt. Other por- 

 tions of the membrane would furnish much more sharply pointed teeth. 



The genital system resembles exactly that of T. palliata, Say, as figured by 

 Dr. Lcidy, Vol. I. VI VII. Fig. 8. (See above.) 



Triodopsis appressa, Say. 



Vol. ni. PI. XIII. 



Shell with the umbilicus covered, orbicularly depressed, pellucid, with rib- 

 like stria; and minute revolving lines, reddish horn-colored; spire flattened; 

 whorls 6, flattened above, the last obtusely angular (the angle obsolete anteri- 

 orly) ; aperture oblique, compressed, subtriangular ; peristome angularly 

 broadly reflected, thickened within, its terminations joined by a thin callus, on 

 which is an obliquely entering, erect, curved, tongue-shaped tooth, the basal 

 margin with a lamellar-like, long denticle, the right margin sometimes with an 

 erect tooth-like callus. Greater diameter 18, lesser 15 mill.; height, 8 mill. 



Helix ap2)rcssa, Say, Journ. Phila. Acad., II. 151 (1821) ; ed. Binney, 15. — 

 BiNNEY, Bost. Journ. Nat. Hist., III. 356, PI. Vlll (1840); Terr. Moll., II. 

 140, PI. XIII. — DeKay, N. Y. Moll., 27, PI. II. Fig. 11 (1843). — Pfeiffer, 

 Mon. Hel. Viv., I. 317 ; in Chemnitz, Conch., 2d ed., I. 361, t. LXIII. Figs. 

 17, 18. —Reeve, Con. Icon., No. 689. — Deshayes in F£r., Hist., I. 141. — 

 W. G. Binney, Terr. Moll., IV. 59 ; L. & Fr.-W. Sh., I. 126, Fig. 211 (1869). 

 — Bland, Ann. N. Y. Lye, VII. 432. 



Helix lingidfera, Lamarck, An. s. Vert., VI. 90 (1822). — F^eussac, Prodr.,'95; 

 Hist., PI. XLIX. a, Fig. 3. —Deshayes, Encycl. Metli., 11. 224 (1830); in 

 Lam., VIII. 70; ed. 3, III. 293. —Pfeiffer, Symb. ad Hist. Hel., 19 (no 

 descr.). — Chenu, 111. Conch., PI. XII. Fig. V; PL VIL Fig. 6.— Deles- 

 SERT, Recueil, PL XXVI. Fig. 5 (1841). 



Xolotrema appressa, Tryon, Am. Journ. Conch., III. 50 (1867). 



In Pennsylvania and New York it is not found east of the Appalachian 

 Chain. From thence it ranges to Arkansas, and from Georgia to Illinois. It 

 may thus be considered a species of the Interior 

 riff. 197. Region. It is best developed in Tennessee and '^' 



Georgia. 

 „ Animal resembling, externally, T. palliata. 



Fig. 197 represents a smaller, more angular form. 

 Fig. 198 represents the var. a of Say, which has two weU- T. appressa, 

 developed teeth on the peristome. I have received it from Vir- 

 ginia, Tennessee, Kentucky, Ohio, Indiana, and Illinois. 



The jaw is very strongly arcuate, of uniform width throughout; anterior 

 surface with 15 ribs, denticulating both margins. 



Lingual membrane with 105 rows of 40 — 1 — 40 teeth each; another mem- 

 brane (PI. VIL Fig. Q) had 33—1—33 teeth; about 12 perfect laterals. 

 The fourteenth tooth has a bifid inner cutting point. 

 VOL. IV. 20 



