OF WESTERN SIND. 299 



3. C(ELOPLEUEUS SiNDENSis, Buncan & Sladen. Plate XLVI, Fig. 6 (young form). 



Description of a young form, about one half of the size of the matured indi- 

 vidual : — 



The test is low, nearly flat above, where there is a very slight rise from the 

 ambitus, tumid at the sides, and rounded actinally where the test is narrowed, and is 

 concave, with a reentering surface. The greatest width is above the ambitus and 

 where the slight slope begins to the apex from the sides. From that zone the test 

 slopes very gradually at first to the narrowed surface on which it rests, and then the 

 surface becomes nearly flat, the convexity being but slight towards the small peristome. 

 The outline of the test is nearly circular from above, and there is no projection of the 

 ambulacra at the upper part of the test, and indeed the only elevation there is the 

 raised series of structures that line the interradia near the poriferous zones. The flat 

 ambulacral surface is very well defined, and the angle made by the poriferous zones is 

 not large. The general absence of tubercles of any considerable size above the position 

 of the greatest breadth of the test is very striking. 



The apical disk is very developed, and the star-like form, produced by the long basals 

 which trespass upon the interradia very considerably, is well marked. The orifice for 

 the periproct is rather large and circular, and there is no prominent ring-like edge to it. 

 Nevertheless the edge of the periproct is high and the basals slope gradually but decidedly 

 to their adoral ends. The madreporite is in the largest and the perforated portion is 

 restricted to a space aboral to the ovarial pore, and reaching not quite to the anal edge. 

 Between the madreporite perforation and the periproct the surface is ornamented with a 

 few large rounded granules, mixed with some smaller, and all are close and irregularly 

 placed, except towards the radial plate No. III. where there is a slight linear set of 

 granules directed outwards and adorally. The largest of the granules is close to the peri- 

 proct, and is about mid-distance between the lateral sutures of the basal. The next basal. 

 No. 3, has the same kind of large and small granules as the other, and although they 

 are wanting at the angle beyond the pore, they are in decided oblique rows elsewhere, 

 and the direction of the close granules is outwards and downwards, so as to put the 

 lines of the ornamentation in continuity with that of the radial on either side. There 

 is a relic of a large granule in the same relative position as in the madreporite. There 

 is also a slanting in of the anal edge and an ornamentation of the part. Basal No. 4 

 is well developed in the specimen, and there is no doubt that in it, as well as in the 

 less preserved basals, the pore is placed on a conical elevation about one third of the 

 whole distance from the angle to the periproct. The ornamentation is of a few separate 

 granules, many of which have become fused, as it were, and are in continuous short 

 oblique lines that have the same relative direction as in the last-mentioned basal. 

 This obliquity is seen on all the basals. The ornamentation of basal No. 1 is very 

 profuse, and there are five rows of oblique sets of large and small granules on one side 

 of the rather tumid plate ; the elongation of some of the granules is very distinct. On 

 the other side the ornamentation is less in amount, but is quite as well defined. Nearly 

 twenty granules may be counted on this basal between the pore and the anal 



edge. 



2s 2 



