OF WESTERN SIND. 157 



Locality. In the Khirthar series : Twenty-four miles west of Kotri (entering the 

 hills on the road to Btila Khan's Thana). Survey-number ^^. 



Illustrations of the Species in Plate XXVIII. 



Fig. 7. Abactinal view of the test : natural size. 



8. Actinal view of the test : natural size. 



9. Longitudinal profile of the test : natural size. 



10. The apical disk : magnified. 



11. A portion of the petal about midway between the apex and the extremity: 



magnified. 



3. EcHiNOLAMPAS OBESA, Dimcan & Sladen. Plate XXVIII, Figs. 12-16. 



Test rather large. Marginal contour regularly oval, the breadth being about 

 four fifths of the length or in the proportion of 0-8 : 1. The outline at the ambitus is 

 well rounded in front and almost equally so behind, there being only the faintest trace 

 of flattening in the curve behind the extremities of the posterior petals. The apical 

 summit of the test is subcentral, and its height is about three fifths of the length of 

 the test, or as 0*59 : 1. Seen in longitudinal profile the dorsal surface is full and 

 convex, the posterior curve being fuller and more convex than the anterior ; the 

 posterior curve is uninterrupted by any marginal tumidity until it reaches the periproct ; 

 whilst the anterior curve passes gently over the thick and tumid anterior margin. 

 Seen in transverse profile the dorsal convexity has a slightly conical appearance, 

 merging imperceptibly into the marginal part of the test, and then curving rather 

 sharply over on to the actinal surface. When seen from behind the periproct is wholly 

 visible, being situated within the margin. The actinal surface is very tumid and 

 pulvinate, the rounded summit of the tumidity midway between the ambitus and the 

 peristome being the only resting plane of the test. 



The apical disk is rather large and is placed considerably in front of the summit 

 of the test, its distance from the anterior margin being about two fifths of the length 

 of the test. The four genital pores are large and oval, and the anterior pair are nearer 

 together than the posterior pair. The central portion is large, rather prominent, 

 undulating, subtuberculate, with a few small widely-spaced granules, and the whole 

 surface covered with the perforations of the madreporite. The ocular plates are very 

 small, subtriangular in shape, and their foramina microscopic. 



The ambulacral petals are long and comparatively narrow ; the posterior pair are 

 the longest and rather broader than the others, and the odd anterior ambulacrum is the 

 shortest and narrowest. The posterior petals are slightly curved, with the convexity 

 towards the posterior interradium. The poriferous zones diverge >gradually in all the 

 petals as they proceed from the apex, and their convergence towards the outer extre- 

 mity is scarcely perceptible, not exceeding half a millim., their outline being in conse- 

 quence wedge-shaped rather than petaloid. The greatest breadth of the postero- 

 lateral petal is 8 millim., or about rob~o of the length of the test. In the antero -lateral 



T 



