EUBTCHLAMYS. AUSTENIA. 191 



with one cusp on the outer side ; outer laterals witli two even 

 termiual cusps as usual in Macrochlamys. 



[To this genus may belong such forms as umhrina, nejpas, 

 luoodiana, &c., provisionally placed in Macrochlamys.'] 



Genus AUSTENIA. 



Austeuia, Nevill {suhgenus of Helicarion), Iland-l. i, 1878, p. 16; 



Godwin-Austen, P. Z. S. 1880, pp. 294, 298 ; id. Mol. Ind. i, 1883, 



p. 148, 1888, p. 228. 

 Girasia, partim, Godwin-Austen, Mol. Ind. i, 1888, p. 21(5. 

 Cryptibycus, Cocherell, A. M. N. H. (.''.) vii, 1891, p. 99 ; id. Nautilus, 



xii, 1898, p. 10 (no description). 



Type, A. gigcs, Bs. 



Range. The Himalaya, Assam, and Burma. 

 Shell imperforate, ovate, of one to two whorls, very thin as a 

 rule, often glassy ; aperture very large, more or less ovate ; pei-istome 

 thin, almost membranaceous. 



Animal large, not retractile within the shell. The lobes of the 

 mantle are united around the shell, and when the animal is 

 extended they cover much of the anterior part of the foot and 

 the greater part of the shell. Each shell-lobe is roundly 

 expanded upon the shell, not elongate as in Macroclilamys. In 

 some forms, as A. magnifica, the shell is nearly or quite concealed 

 by the mantle-lobes, as in Girasia, while in the type a considerable 

 portion remains exposed. 



Hinder extremity of foot long, sharply carinate above and 

 truncate behind by a large linear mucous pore, above which there 

 is sometimes an overhanging lobe. Pei'ipodial groove very distinct. 

 Sole of the foot divided into three longitudinal areas. 



Genital aperture, as usual, behind the outer base of the right 

 tentacle. The details of the generative organs much resemble 

 those of MacrocJdami/s, except that near the retractor muscle of 

 the male organ there is neither caecum nor coil. A large dart-sac 

 is present and a long cylindrical spermatheca. 



In the radula, which nnich resembles that of Macrochlamys, 

 the rhachidian is tricuspid, and the admedian teeth are broad and 

 bicuspid or tricuspid. The outer laterals are long and pointed, 

 with an additional cusp low down on the outer margin, and 

 which disappears on the outermost teeth. This differs from the 

 form of the outer marginals in Girasia. 



The genus Austeuia is intermediate between Macrochlamys and 

 Girasia and distinguished from all by its ovate ear-shaped shell. 

 It is less slug-like than Girasia, its shell being well formed and, 

 as a rule, less covered by the mantle. It is represented in the 

 Indian Peninsula by the genus Psemhiustenia, which has a similar 

 shell, but several differences in the animal. 



