OF WESTEEN SIND. 



-No. III. Zone " a "—Plate 9, small deml. 



10, large primary. 



11, small demi. 



297_ 



Zone " h " — 9, large primary. 

 10, small demi. 



In the zone " a " the tubercle-bearing plates are Nos. 4 and 7, whilst those of the 

 other zone are Nos. 6 and 9. After the triplets on zone " « " formed by Nos. 6, 7, 8, 

 comes a very large tubercle-bearing plate composed of plates 9 a demi, 10 a very large 

 plate, and 11a demi. 



In the zone " h " the tubercle-bearing plates are Nos. 6 and 9 and the triplets are 

 Nos. 5, 6, 7, and 8, 9, 10. The sutures between the great tubercle-bearing plates of 

 the ambulacra are very distinct, in sunken grooves. At the median line, where the 

 sutures intersect, there is sometimes a pit even close to the ambitus. Nearer the 

 actinostome the usual development of the large pit at each angle of the plates 

 along the median line is seen, and there is no doubt that the shape of the pit is that 

 of a broad archway with a flat floor. The pits are large for the size of the test. Two 

 are close together just at the edge of the peristome ; these are the largest, and they are 

 so well preserved that the little process for the sphseridium is visible. In parts the 

 denticulate sutural edge of the ambulacral plates is quite visible under a low power. 

 The pairs of pores are in simple triplets to the peristome and there are no additional 

 pores in the arcs. 



The apical ring is well developed, and the orifice is subcircular and large, and the 

 whole of the combination of plates is somewhat raised beyond the rest of the test. 

 The basal plates are large and subequal, with the outer angle rather blunt and 

 projecting well into the interradial area. The ovarial pores are large, and placed at 

 about the outer third, and there appear to be the remains of a small tubercle 

 between each one and the periproct. The radial plates are large, well separated from 

 the periproct by the junction of the basals, and the adoral edge is concave and has the 

 relics of a small central downward-projecting process. There is no perforation for the 

 optic nerve, and this evidently came out beneath and below the concave adoral margin, 

 and was separated into two by the process just noticed. Unfortunately the ornamen- 

 tation of the radials has been worn off"; but this erosion has exposed the interesting 

 denticulate dovetailing of the plates at their lines of sutures. The denticulation is 

 visible between the basals and the radials and also between these and the first plates of 

 the interradia. 



This small specimen came from the Gaj group ; but the locality is not stated. 



Illustrations of the Form on Plate XL VI. 

 Fig. 4. The test : natural size. 



Numerous specimens of a Coelopleurus which, although clearly allied to Ccelopleunis 

 Forhesi, are not of the same species, are found in the Gaj deposits. The specimens did 

 not come from the same localities as Ccelopleurus Forhesi, but we are not informed 

 about there being any difference in the geological horizons of the two sets of forms. 



2s 



