92 ZOXITIVJE. 



The generative organs present very remarkable variation from 

 typical Macrochlamys, particularly in the form of the penis. The 

 kale-sac is very long, quite a flagellum, and close to where the retractor 

 muscle is given off there is a long free ccecum loosely coiled ; this 

 undoubtedly represents the closely-wound ccecum in the type species, 

 to the side of which the retractor muscle is usually attached. In this 

 species the ccecum is quite free, the retractor muscle rising at the base 

 of the ccecum itself. The spermatheca is also very long and 

 abnormal in form, consisting of a capacious thin-walled sac at the 

 extremity of a thick muscular stalk-like tube, equal in length to 

 the sac it terminates in. The amatorial organ is thick and large, 

 with a very strong lengthened retractor muscle. 



Here comparison must be made with the generative organs of 

 M. sathilaensis and M. zamoensis. In both species the penis 

 presents a similar departure from that of typical M. indica ; in 

 both the penis ccecum is free and loosely coiled, merely kept to- 

 gether by a few muscular fibres, whereas in M. indica this caecum 

 is closely coiled into a mass impossible to unroll, and this is the 

 dominant type over an extensive area of country.] 



[134. Macrochlamys sathilaensis, Godwin-Austen, Mol. Ind. ii, 

 1907, p. 169, pi. 106, figs. 4-4 c (shell and anatomy). 



Shell globose! y conoid, translucent, delicate structure, nar- 

 rowly umbilicated ; sculpture confined to some very delicate 

 fine longitudinal striation near the suture, which dies out, and the 

 rest is perfectly smooth, crossed transversely by wavy furrows ; 

 colour pale ocliraceous ; spire moderately high, conoid ; suture 

 moderately deep; whorls 6, gradually increasing; aperture widely 

 lunate, oblique ; peristome very seldom quite perfect. 



Size : maj. diam. 13-5, min. 12*0, alt. axis 6-5 mm. 



Locality. Kicbila Peak, Bhutan frontier. 



This shell, which has very much the coloration of M. sequa&\ 

 differs altogether in form. It belongs to a group very similar one 

 to the other, very common, and very variable with locality. 



Animal. Colour throughout pale ; no markings, only a slight 

 grey tinge near the head. The withdrawn tentacles are very 

 black, and in life probably show as dark lines on the neck ; pallial 

 margin finely streaked. The shell-lobes and extremity of foot as 

 in M. sequim from Damsang ; and the radula is of the same type 

 exactly : 



+ 31 . 2 . 11 . 1 . 11 . 2 . 31 + 

 + 44 . 1 . 44 + 



The smaller teeth near the margin would add another 10 or 15 to 

 the above, or about 90 in the row. 



The jaw is well arched, with a large central projection. 



The visceral sac is closely mottled, and shows dark inside the 

 shell. 



