148 LAND AND FRESHWATER 
Subgenus Avsrenta, Nevill. 
Helicarion, Fér., of many authors. 
Vitrina, Fér., of many authors. 
Austenia, Nev. Hand-list, p. 16 (Dec. 1878); Godwin-Austen, 
P.Z.8. 1880, p. 294. 
This as a subgenus of LHelicarion was indicated by Mr. Geoffrey 
Nevill in his valuable ‘ Hand-list of Mollusca in the Indian Museum,’ 
Calcutta, part 1, issued in December 1878. It was not described, 
but the type was indicated, viz. A. gigas, a well-known form on 
the Khasi Hills. It is a sufficient departure structurally from 
Girasia of Gray to retain, this latter being more slug-like and 
with usually far less developed shells. In a paper in the ¢ Pro- 
ceedings of the Zoological Society,’ April 1880, p. 289, the animal 
of A. gigas was described by me in detail, as well as that of Grrasca 
shillongensis, and the two compared, and the plates (xxiv.—xxvii.) con- 
tain figures of Girasia magnifica, shillongensis, brunnea, and hookeri 
(the type), and Awstenia gigas and gigas var. minor, A list of 
the species as then known in both subgenera was also given and 
can now be somewhat added to and amended. 
Characters of the subgenus. 'The animal is somewhat slug-like in ap- 
pearance, but with a well-formed shell. The shell-lobesample. The 
right dorsal lobe extends from the respiratory orifice to the posterior 
right margin. The left dorsal lobe is large in front and extends from 
the same part to the left margin. The shell-lobes are connected all 
round the periphery of the mantle-zone, but are reduced in size 
and present two distinct right and left contractile lobes; the right 
extends to and covers the apex of the shell, while the left extends 
over the edge of the body-whorl for a short distance, leaving the 
posterior and the greater portion of the upper surface of the shell 
uncovered (we have here, in a more developed form, what is seen 
in the genus Macrochlamys). The posterior margin of the shell is 
not sunk in a depression of the hinder part of the foot, but the 
upper surface of the foot extends in an unbroken ridge to the mantle- 
zone. Extremity of the foot truncate, with a large linear mucous 
gland, with or without an overhanging lobe ; the pedal line very dis- 
tinct. The sole of the foot with a central separate area. 
Genital aperture at the lower outer base of the right tentacle. 
The generative organs may be compared with those of Macro- 
chlamys indica &c., and are, as might be expected, very similar ; the 
amatorial organ is always present and well developed, and the 
spermatheca is large. ‘The male organ, however, never has the 
coiled czecum near the retractor muscle attachment so typical of all 
the species of Macrochlamys. The spermatophores are remarkably 
well formed and beautiful objects. The teeth of the radula and jaw 
as in Macrochlamys indica. The type and other species will be 
figured in future parts. 
