3 70 LAND AND FRESHWATER 



free coecum close to the retractor-muscle attachment of the male 

 organ, which undoubtedly represents the close coil of the type 

 species of the genus Macrocldainys, more or less solid in other 

 species. It shows so well the origin of this coil, and further that 

 the above three species are the older in the line of development. 

 Following on this, it points to this area of the Eastern Himalaya 

 being the centre of dispersal of the genus. The geological evidence 

 tends to show it is an ancient land-area from Sikkim eastward up 

 to the margin of the present plains, an area probably coeval with 

 that of Peninsular India, and once connected with it across what is 

 now the delta of the Ganges. 



1 have hitherto in this work, following Nevill, retained Austenia 

 as a subgenus of the Helicarioninae. I now consider it should take 

 its place as a genus of the subfamily Macrochlamyinee, together with 

 Girasia and Cri/jjiosoma. Ihycus, as I shall show, belongs to the 

 subfamily Durgellinoe. 



Genus Austenia. 

 (Contiimed from Vol. II. p. 109.) 



Austenia silcharexsis, n. sp. (Plate CYII. figs. 1-3 a.) 



Locality. Near Silchar, Cachar {F. Ede). 



Shell (tigs. 1, 1 rt, 1 b). The description of ^. bensoni will apply 

 generally. It is bright and shining, of a straw-colour. Three whorls, 

 these are flatter above than in that species, making the aperture 

 wider horizontally to the axis ; viewed from above, the last whorl 

 spreads and widens out\^ards as it nears the aperture. 



Size : raaj. diam. 0*95, alt. axis 0"35. 



Animal (%s. 2, 2 a). Preserved in spirit is pale vinous, greyer on 

 the sheU-iobes ; on the side of the foot, just above the peripodial 

 groove, are a series of isolated dark blotches. The foot is long behind, 

 narrow compressed at the sides, and terminating in a long hooked 

 point overhanging the narrow slit of the mucous gland. The sole 

 is very distiuctly divided. The peripodial groove and margin not 

 so distinctly marked as in some species. The right and left 

 shell-lobes are remarkably developed, particularly the former ; 

 })road and expanding, in life evidently covering the whole shell, 

 they have a beautiful papillate surface. The length of this specimen 

 (contracted) is 2'25 mm. 



Genitalia (figs. 3, 3 «). The amatorial organ is long and cylindrical, 

 tapering gradually to the retractor muscle. The penis is bent 

 sharply where the long retractor muscle is given off, then there is a 

 short swollen part where the si)ermatophorc would be formed, and 



