MANUAL OF THE MOLLUSCA. 
Animal unknown ; habit subterranean. 
Shell similax to that of Achatina acicula, but the columella is 
not truncated, and the outer lip is thickened. 
XANTHONYX, Crosse and Fischer, 1867. 
Type, Vitrina Sumichrasti, Brot., Mexico. 
Animal elongated, too large for complete retraction into the 
shell; jaw like that of Avion; lingual dentition consisting of a 
series of uniform teeth, with a broad and subquadrangular base ; 
the median tooth with a large central cusp and denticle on each 
side; the laterals are bicuspid, the internal cusp long, the 
-external short 2nd obtuse, sometimes accompanied with the 
rudiment of a third; pulmonary orifice near the middle. 
Sell imperforated, very thin, transparent, subdepressed, 
intermediate in form between Vitrina and Simpulopsis. 
Distribution, 3 species. Mexico. 
Faminy I1.—LimaAcmz.* 
Hyatimax, H. and A. Adams. 
Type, Limax perlucidus, Quoy. 
Animal limaciform, mantle large, shield-shaped ; pulmonary 
orifice medial and marginal; foot attenuated behind, no mucus 
gland, separated below from the head by a distinct groove; 
jaw analogous to that of Zonites with the support of Succinea ; 
lingual dentition with a tricuspid median plate, laterals with a 
large cusp, supporting two or three denticles. 
Shell internal, rounded, thin, and slightly arched above. 
Distribution, 2 species. Bourbon, Mauritius. 
KRYNICKIA, Blainyille, 1839. 
Dedicated to the naturalist Krynicki. 
Type, Limax megaspidus, Blainville. 
Animal limaciform, but the anterior part of the mantle is free 
and detached from the body as far as the pulmonary orifice, 
which is situated far back. 
Shell internal, flat, lamellose, elliptical, with no spiral 
nucleus. 
Distribution, 8 species. Orimea, Caucasus, North America 
(1). Central America (1), 
PuILoMycus, Rafinesque (p. 298). 
Type, Limax Carolinensis, Bosc. 
* See p. 205. 
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