178 



[276. Dalingia bhutanensis, Godwin-Austen, Mol. 2nd. ii, 1907, 

 p. 149, pi. 102, figs. 1-6 (shell and anatomy). 



Shell depressedly conoid, very narrowly umbilicated, allowing 

 the passage of a fine bristle, thus the umbilicus is almost hidden. 

 Sculpture, to the eye, transverse wavy lines of growth ; under 

 lens, longitudinal furrows are seen crossed by narrower ones, 

 breaking the surface into irregular decussation. Colour rich 

 olivaceous brown. Spire low, apex flatly conoid ; suture im- 

 pressed. Whorls 4, tumid, convex ; aperture widely lunate, 

 peristome thin. 



Size : major diam. 20*5 mm.; alt. axis 9*5 mm., alt. body- whorl 

 10*5 mm. 



Locality. Bichila Peak, on the Sikhim-Bhutan frontier. 



Animal can retire completely within the shell, and the speci- 

 mens had been taken during hibernation, for the aperture was 

 covered with a strong epiphragm, tough and transparent. It is 

 dark-coloured. Sole of foot with a distinct central area. There 

 are no shell-lobes ; the left dorsal lobe is divided. 



The peripodial margin is broad, bordered above with a double row 

 of oblong tubercles, or, in other words, there are three parallel grooves 

 instead of the usual two. 



Generative organs. The amatorial organ is absent. The retractor 

 muscle of the male organ is given off from the head of a large 

 ovate swollen mass, which corresponds to the coiled mass seen in 

 Oxytes orobia. There is a short flagellum or kale-sac. The sper- 

 matheca is moderately long and consists of an ovate membranous 

 portion situated on a lower thick muscular tube ; the albumen- 

 gland was small ; the hermaphrodite-duct extremely convoluted. 



Jaw with a large central projection. 



The radula has this formula : 



40 . 2 . 17 . 1 . 17 . 2. 40 

 59 . 1 . 59 



The central tooth is tricuspid, the admedians also tricuspid, the 

 inner well developed and standing higher than the outer, which is 

 the largest. The marginals are curved, bicuspid, the outer cusp 

 below the inner. 



Of this species there were only two specimens in the B. M. 

 collection with similar sculpture on the shell one, an adult, from 

 which the above description has been made, and another much 

 younger example left in the shell ; the pallial margin and markings 

 on the visceral sac are the same in both. 



The anatomy of this animal is very unlike that of those with 

 similar shells. 



It is remarkably like another in its shell-character inhabiting 

 the vicinity of the same peak, Eichila. On first sorting- 

 out of a quart-bottle of shells from this locality I placed them 

 together ; on a second sorting I noticed considerable difference 

 in the sculpture when this was looked at under a high power, 

 combined with a modification in the form of the shell, of that 



