ANOSTOMA. 109 



Var. venezuelensis Pfeiflfer. 



Slightly smaller than T. cumingi, the spire a little less conic; 

 whorls 4. 



Alt. 5, greater diam. 6^, lesser 4^ mill. (Pfr.). 



Alt. 5-J, greater diam. 6f, lesser 4 mill. (Caracas specimen). 



Alt, 5^, greater diam. 5J, lesser 4^ mill, (specimen). 



Venezuela (Curning coll., R. Tate); Caracas (F. Cocking). 



Genus ANOSTOMA F. de Waldheim, 1807. 



Anostoma F. de W., Museum Demidoflf, ou Catalogue Systema- 

 tique et raisonne des curiosites de la nature et de Fart donnees a 

 FUniversite Imperiale de Moscou par S. E. M. Paul de Demidoflf, 

 iii, p. 230 (1807), for A. octodentata and A. hexodon. Tomogeres 

 MONTFORT Conch. Syst. ii, p. 358 (1810), for T. ringens = A. octo- 

 dentatum JOUSSEAUME, Bull. Soc. Zool. de France, 1877, p. 311 ; 

 TomogeridcB of the same author, 1. c. Tomogerus BLAINVILLE, Diet. 

 Sc. Nat. xxxii, p. 252 Angystoma SCHUMACHER, Essai, etc., p. 

 229 (1817), for A. resupinata = A . octodentatum. Anastoma JAN, 

 Catal., p. 2 (1832), and of some other authors. 



Shell heliciform, biconvex, solid, the axis hollow, but imperforate 

 in the adult stage ; composed of few whorls, the last straightened, 

 turning toward the margin and upward ; the semicircular aperture 

 turned upward, obstructed by numerous lamellae and folds ; peristome 

 expanded and reflexed. 



Jaw smooth, arcuate (pi. 5, figs. 32, 33, A. ringens}. Teeth as 

 in terrestrial Holopoda generally, the centrals and laterals with single 

 broad cusps, marginals short, with the ectocone developed (pi. 5, fig. 

 39). Genitalia (pi. 5, fig. 26) of the haplogonous type, the long 

 slender penis passing into a long vas deferens, upon which the penis 

 retractor muscle is inserted ; duct of the globular spermatheca ex- 

 tremely long. Cerebral ganglia (pi. 5, fig. 34) connected by a short 

 narrow commissure; suboesophageal ganglia (pi. 5, fig. 35) as usual 

 in Bidimulidce. 



Type, A. octodentatum F. de W. Distribution, tropical South 

 America, east of the Andes. 



One of the most peculiar genera of land snails. The prominent 

 feature of an upturned aperture (causing the adult snail to carry the 

 shell spire down) is happily expressed in its name (ana, up, and 

 stoma, mouth. Up to the last half whorl, the shell is umbilicate, and 



