MOLLUSCA. 5 



P. mmcorum at all, the spire is less produced, striation less developed, form of aperture simpler 

 and less angular ; length 2f mm. ; no tooth. 



Not a single one of the Ladak specimens possesses even a rudiment of a tooth on the 

 wall of the aperture, nor have I been able to detect any in the Kaskasu form ; in one or two of 

 the Pasrobat shells only is a very slight tooth just discernible ; as far as I have seen, this 

 absence of the tooth appears to be characteristic of our Asiatic forms. 



10. PTIPA (PUPILLA) CHISTATA, v. Mart. 



E. v. Martens, Fedsch. Reise, Moll. pi. ii, fig. 19 (Sarafshan Valley). 



The specimens of this very distinct and interesting form agree exactly with typical 

 figures 19C. and E. Figure B, on the contrary, has the spire a little more produced, with 

 the whorls a trifle more convex, and the aperture slightly more contracted, the margins 

 of which, in our Museum specimens, are somewhat considerably more delicately dilated ; I can 

 only detect, after a most careful search under the lens, a single tooth on the outer margin, 

 as in the above figure C, not two, as in the description and figure B. 



Shell ovate, rimate, of horny brown colour, obliquely slightly striated, apex obtuse ; 

 seven whorls, the 4th, 5th and 6th of equal width, the last one somewhat compressed at the 

 base, with an obtuse keel round the umbilicus continued more prominently in a raised ridge, 

 parallel with the outer margin of the aperture ; aperture small and rounded, with the peristome 

 broadly reflected; a prominent tooth on the wall of the mouth, a single fold on the columella 

 (lying rather far back) and a single obtuse tooth within the outer margin. Long. 3^, 

 diam. 2 mm. 



Eleven specimens from Sasak Taka, where it is by no means common; sixteen from 

 Pasrobat, where it occurs more abundantly in company with P. mmcorum. 



11. STJCCINEA MARTENSIANA, n. sp., Figs. 30-31. 



Shell unusually thick, about the size of S. girnarica, Theob., (Conchologia Indica, 

 pi. Ixvii, fig. 6,) which it at first sight much resembles ; it is, however, quite half as thick 

 again, of much intenser colouring and of more convexly shaped whorls ; whorls four, convex, 

 produced and separated : in S. girnarica there are only three, which increase less rapidly and 

 are less obliquely inclined ; the last whorl of the Yarkand species is shorter and not nearly 

 so ovately oblong ; the texture is more rugose, the irregular longitudinal furrows being 

 unusually strongly developed ; the colouration is peculiar, being of an opaque milky white, 

 more or less purple near the apex ; the aperture is internally of a brilliant orange colour and 

 more laterally expanded than in S. girnarica : the columella varies, but is always straighter 

 than is the casein its ally; the callosity joining the columella and outer lip is strongly marked. 



S. martensiana (type), long. 17, diam. 11; apert. long. 12, diam. 8^ mm. 



S. girnarica, long. 18^, diam. llf ; apert. long. 14, diam. 9|- mm. 



This species is very variable in shape ; the Museum possesses a very fine series of it, all 

 from Kathiawad (Kattywar). 



I have named this handsome species after Dr. E. von Martens of Berlin, to whose great 

 kindness, in sending me a critical opinion of these Yarkand shells, I am so much indebted. 



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