100 PROVISIONAL AID TO THE STUDY OF TASMANIAN MOLLUSCA. 



semi-lunar, with or without interior teeth on the 

 margin or parietal wall ; lip simple or thickened 

 internally or reflected, umbilicus covered, widely open. 

 Dist. — Universal . 



Genus Bulimtjs. (519-520.) Land Shells. 

 Shell oval-oblong or turriculated, solid, sub-perforate or im- 

 perforate ; whorls few, the last ventrieose and large ;. 

 aperture longitudinal ; columella widened, rarely 

 plicate ; peristome thickened, reflected ; the lip 

 usually joined by a callus. Did. — Mostly South 

 American. 



(lx.) Family Pupidye. (Land Shells.) 

 Shell generally minute, multispiral, cylindrical, with obtuse 



summit (pupiform) ; aperture small, usually contracted 



by internal teeth or lamellae. 



Genus Pupa. (521.) 

 Shell usually very small, cylindrical or oval- oblong; umbilicus 



slight or a mere slit ; plicate, striate or costellate 



brown or horn-colour ; columella plicate or sub-dentate ; 



lip reflected, usually dentate or plicate within, the 



extremities usually joined by a raised callus. Dist. — 



Universal, boreal and tropical. 



(lxi.) Family Limacid^;. (Terrestrial Land Slugs.) 

 Shell rudimentary, a calcareous plate, not spiral, concealed under 

 the mantle, and covering the respiratory cavity. 

 Genus Limax. (522.) 

 Shell-plate testaceous thin, flat, longer than wide, with con- 

 centric striae of increase, internal. Dist.' — Universally 

 distributed. 



(lxii.) Family Arionid^e. 

 (Animal naked, with or without mucous pore ; mantle conceal- 

 ing a shell-plate, or a few calcareous grains which 

 represent it ; jaw strongly ribbed ; central tooth 

 tricuspidate, the median cusp long and narrow ; 

 laterals and marginals bicuspidate.) 



Genus Cystopelta. (523.) 

 Body attached for half its length to the back of the foot ; 

 mantle very large, enveloping the whole animal in 

 repose, but from beneath which the head and the tip 

 of the tail alone are visible from above when the 

 animal is crawling; tentacles four; tail with a 

 mucous spore at the tip ; mandible like that of Arion ; 

 lingual teeth resembling those of Testacella. No 

 shell. Dist. — Tate. Tasmania. 



