OF WESTERN SIND. 75 



antero-lateral ambulacra form a very open angle, are nearly closed ; the conjugate grooves 

 are oblique, and the posterior poriferous zone is more curved than the anterior. The 

 postero-lateral ambulacra are nearly closed, are rather close together ; and the conjugate 

 grooves are oblique. The extremities of these ambulacra are about 1^ times the 

 length of the petals from the periproct. The interporiferous zones of the lateral 

 ambulacra are narrow distally, and in all cases are sparsely ornamented like the sur- 

 rounding interradial area. 



The interradial areas are large, and are separated by the long continuations of 

 the ambulacra beyond the petaloid portions. These continuations are broader than 

 the ambulacra as they reach the margin, although narrow at the end of the petals ; 

 they are marked by a series of solitary pores on either side. The posterior interambu- 

 lacrum is rounded between the ambulacra, and then slopes with a very equal convexity 

 backwards and downwards, forming hardly a trace of keel, and reaches the periproct. 

 The ornamentation of all the interradials is small, close, equal, and consists of small 

 tubercles in sunken scrobicules, the intermediate raised portion of the test being 

 scanty. 



The peristome is sunken, subcentral, pentagonal, largest transversely, and deep. 

 The floscelle is moderately well developed. The bourrelets are narrow and project 

 downwards, with rounded edges; and the phyllodes are not petaloid, but are open 

 externally and small peristomially. There is a shght reduplication of pores, and the 

 first pair are very visible at the peristomial edge. 



The actinal ornamentation is of the same character as the abactinal, but slightly 

 larger. 



Just above the rounded-off posterior margin the test is very slightly truncated ; 

 and there is a shallow median groove with a faint ridge on either side leading up 

 to the periproct. 



The length of the type is i% inch, and the extreme breadth is the same; the 

 height is -^g inch. 



Locality. Hills east of Lynyan, gypseous shales in the Eanikot series. Survey- 

 number G xf 6*- 



Illustrations of the Species in Plate XVII, 



Fig. 1. View from the side : natural size. 



2. From behind : natural size. 



3. The apical system and petals : magnified. 



4. The peristome : magnified, 



Eemarks. This species is very nearly allied to P. pileus, but difiers in the more 

 conoidal and more tumid form of the test. The periproct is higher up, the median 

 keel and the overhanging supra-anal ridge are much less developed, and the infra-anal 

 groove is narrower and more clearly defined. The ambulacral petals are comparatively 

 smaller, and the interporiferous areas narrower, than in the preceding species. These 

 differences appear sufficient to warrant the recognition of the independence of this form, 



