168 HELIX-LABYRINTHUS. 



stome, and very abruptly deflexed; base with two pits immediately 

 behind the lip, marking the places of the basal lip-teeth ; aperture 

 nearly horizontal, oval-ear-shaped, brown inside; peristome white, ex- 

 panded, reflexed, continued across the parietal wall in an elevated 

 plate-like callous, its edge somewhat sinuous or concave near its junc- 

 tion with the superior lip ; outer lip with a small denticle above (rarely 

 obsolete), a rather large compressed tooth below the carina, and a 

 blunter, rounded, subcompressed tooth on the outer part of the 

 straight basal margin ; parietal wall armed with an elevated lamina 

 or tongue-like tooth, arising from the middle of the lip-connecting 

 callous, extending inward obliquely, directed toward a point on the 

 outer lip above the larger outer tooth ; umbilicus funnel-shaped. 

 Alt. 1(H, diam. maj. 21 2, min 20 mill. 



Alt. 9, diam. maj. 21, min. 19 mill. 



Venezuela. 



H. leucodon PFR. Zeitschr. f. Mai., 1847, p. 81; Conchyl. Cab., p. 

 271, t. 123, f. 12-14; Monog. Hel. Viv., i, p. 399. REEVE, Conch. 

 Icon., f. 558. MARTENS, Binnenmoll. Venez., p. 13. 



Variable in the degree of elevation of spire. Thicker, larger and 

 less elevated than H. tamsiana with stronger teeth, darker colored 

 shell and wider umbilicus. I have seen a specimen in which the 

 inner basal tooth is bifid. The surface feels peculiarly rough. 



H. QUADRIDENTATA Broderip. PI. 41, figs. 12, 13. 



Shell narrowly umbilicated, depressed-conoidal, rather thin, striate, 

 finely but sharply granulate, opaque, reddish-brown, spire flat- 

 conoidal, with broad, flat apex; suture very superficial; whorls 5-i, 

 flat, gradually widening, the last in front somewhat constricted, 

 abruptly deflexed ; beneath, at the positions of the teeth deeply 

 furrowed, the base behind this somewhat gibbosely convex ; aper- 

 ture nearly horizontal, oval-ear-shaped, 4-toothed ; peristome thin, 

 whitish, expanded, somewhat reflexed, the terminations joined by a 

 straight, low, erect lamina ; on the penultimate whorl [parietal wall] 

 stands a tongue-shaped laminar tooth, inside the connecting callous, 

 and not connected with it. The superior margin of the peristome is 

 curved, toothless; on the under lip, near the keel, there is a three- 

 cornered compressed tooth, somewhat curved and erect, and two 

 other blunt teeth, of which the one standing nearest the columella is 

 much smaller. (Pfeiffer, in Conchyl. Cab.} 



Alt. 9, diam 19 mill. 



Central American forests. 



