OF WESTERN SIND. 191 



pairs of small pores in continuation of each zone, widely spaced, the pores small, round 

 and close together. The succeeding pores are simply microscopic. The extrapetalous 

 portions of the poriferous zones diverge outwards towards the ambitus, and again con- 

 verge as they approach the peristome. 



The postero-lateral ambulacra are similar in every respect to the anterior pair 

 above described, and, like them, proceed direct from the apex outwards. The curve of 

 the anterior zone is perhaps slightly fuller near the apex than that of the companion 

 posterior zone, but the difference is so slight that it is only perceptible in some speci- 

 mens. The posterior petals enclose an angle of about 62°. The distal extremity of the 

 petal is more remote from the margin than that of the anterior pair ; and the extra- 

 petalous portion of the ambulacra is of similar character to those above described. 

 Three pairs of pores are well developed within the subanal fasciolar area. There are 

 2-3 to 26 pairs of pores in the poriferous zone of the antero-lateral petals, and usually 

 one to three pairs less in the postero-lateral ambulacra. 



The anterior interradia have a slightly tumid appearance, which is especially 

 emphasized on the abactinal surface, the breadth and shallowness of the depressions in 

 which the petals are placed causing the interradia to seem more prominent than they 

 really are. In the lateral interradia the subcarinate character is less prominent, but is 

 most highly developed in the odd posterior interradium, the narrow space between the 

 postero-lateral petals forming a broad, low, well-rounded keel ; and there is a slight 

 tumidity in continuation of this along the median line of the area extending up to the 

 periproct. The ornamentation consists of very small primary tubercles, punctured and 

 crenulated, situated in a small scrobicule, and widely spaced, the intermediate space 

 being filled with small, low, uniform, well-spaced miliary granules. On the abactinal 

 area the ornamentation is so small that it is only seen under magnification. In the 

 neighbourhood of the mouth it becomes larger, however ; and on the plastron the 

 tubercles are large and uniform, standing on large, prominent scrobicules, which are 

 closely placed, and in parts imbricate or impinge on the neighbouring scrobicules. 



The peristome is very excentric in front, is rather small and transversely oval in 

 outline, and is surrounded by a slightly raised margin. The posterior lip is insignificant, 

 very faintly, produced, and is not prominent ; but there is a rather prominent tumidity 

 behind the lip, and a little remote from its margin, which merges gradually into the 

 median tumidity of the plastron. The ambulacral regions in the neighbourhood of the 

 peristome are slightly depressed. 



The periproct is about equal in size to the mouth, is transversely oval, and situated 

 at the extreme top of the posterior truncation. The general character of this area is 

 on the whole tumid; but in the inferior part there may be a very faint tendency 

 towards a median depression. . 



A broad, well-developed, subanal fasciole encircles the angle of the posterior 

 margin, part being above and part below the rounded angle formed at the junction of 

 the vertical posterior end and the actinal surface. The space enclosed is large and sub- 

 reniform in outline, and the upper part of the fasciole dips down with a rather deep 

 reentering curve, pointing downwards, in the median line. Three pairs of pores 



2c2 



