OF WESTEEN SIND. 321 



actinal surface is much more widely concave, and not plane with a sudden depression to 

 the peristome as in C. Scilloe. 



Variations. We have already remarked on the amount of variation that occurs 

 within the limits of the large series of specimens which we regard as belonging to this 

 species. The variation chiefly affects the marginal contour, the degree of convexity of 

 the abactinal surface, and the character of the interporiferous area of the petals. The 

 marginal contour is more definitely pentagonal and broader in some examples, more 

 elongate and produced anteriorly and with a tendency to a suboval form in others ; and 

 the amount of interradial incurvature is likewise variable. The distinctness and the 

 amount of elevation of the abactinal dome is much greater in some examples than 

 in others, and this apparently irrespective of age. In others, again, the distinct character 

 and abrupt rising of the " dome " is more or less merged in the general convexity of the 

 abactinal area. The amount of tumidity of the interporiferous area of the ambulacral 

 petals is also subject to variation, and appears to be proportionately less in small speci- 

 mens. It may here be mentioned that there are about half a dozen medium-sized 

 examples, the largest 72 millim. in length, from different localities, in which the inter- 

 poriferous areas are comparatively narrow and in which the tumidity is almost, and in 

 some cases quite, wanting. After carefully studying the material at our disposal, how- 

 ever, we do not feel warranted in removing these examples from the present species, as 

 intermediate forms may easily be selected. We consider it probable that one of 

 d'Archiac and Haime's forms would rank along with these just mentioned, whilst the 

 figure of C. profundus given in the Anim. foss. de ITnde (pi., xiv, fig. la and Ih) well 

 represents the variety under notice. C. Halaensis is also an immature form in which 

 the petaloid tumidity is developed ; and it is only just to observe that MM. d'Archiac 

 and Haime themselves appear to have had doubts (loc. cit. p. 208) as to the reality of 

 the difference of this species from C. profundus. It should here be remarked that in 

 quite young examples, 28-40 millim. in length, which we consider to belong to this 

 species, the tumidity of the petals is rarely ever present, and then only in a very feeble 

 degree ; whilst from the general form, character, and occurrence of these small tests 

 we have no hesitation in referring them to the series under notice. 



Dimensions. Length of the test 92 milHm., breadth 84 millim., height 24 millim. 



Localities. In the Gaj series of strata : — 



i. Myhir scarp, Habb valley. Survey-number G ^^. 



ii. Scarp of the M61 Plateau, west of Kund (the same scarp as G ^■^). Survey, 

 number G^f. 



iii. Scarp at Ktipo-jo-lak, or pass on the M61 range, west of Shah-beg (same locality 

 as G ^li). Survey-number G ^^^\. 



iv. Ten miles north of Shah-beg. Survey-number G -^. 



v. About three miles south-east of Tong. Survey-number G ^^. 



vi. Four miles south-west of Beynir Hill. Survey-number G ^3-. 



vii. Scarp six miles south-east of Shah-beg. Survey-number G ^i^-. 



t This specimen is marked G ^ ; as no such Survey-number occurs in the list of Gaj specimens, it is 

 probably an error of the marker, intended for Gc ^^t. 



2x 



