OF WESTERN SIND. 223 



niustmtions of the Species in Plate XXXVII, 

 Fig. 15. Abactinal view of the test : natural size. 



16. Actinal view of the test : natural size. 



17. Longitudinal profile of the test : natural size. 



18. The test seen from behind. 



19. Odd anterior ambulacrum : magnified. 



20. Portion of one of the petaloid ambulacra : magnified. 



21. Apical disk : magnified. 



2. ScHizASTEE siMULANs, Buncan & Sladen. Plate XXXIV, Figs. 15 & 16. 



There is a single badly-preserved and broken test of Schizaster in the collection, 

 which is so well marked that we have ventured to name it, although the condition of 

 the fossil is unsuitable for description, and our remarks are consequently limited to 

 such characters as may be observed. 



The test is of medium size, having the marginal contour oval, deeply indented in 

 front, and rather contracted posteriorly. The apical disk is only slightly excentric 

 posteriorly. Seen in longitudinal profile, the greatest height occurs near to the 

 posterior extremity, and the abactinal area slopes thence gradually to the compara- 

 tively thin anterior margin. The general character of the test is decidedly depressed 

 for the genus, and the margins are comparatively thin and almost angular in their 

 rounding. The groove of the odd anterior ambulacrum is deep and narrow. The 

 anterior pair of petaloid ambulacra are deep, wide, and well rounded at the outer 

 extremity, and contract gradually at the apical extremity ; and the petals as a whole 

 are comparatively slightly curved, and rather widely divergent. The posterior pair of 

 petals are small, subelliptical in outline, and only slightly divergent, and are separated 

 by the ridge-like carination of the odd posterior interradium. 



The anterior and the lateral interradia are not prominently keeled, although their 

 narrowness at the apex, combined with the depth of the grooves of the petals, simulate 

 that appearance near the apical disk. From the point of greatest height the odd 

 posterior carination is abruptly rounded to the posterior extremity, where the test is 

 prominent and overhangs the periproct. This aperture is placed at the summit of the 

 high posterior truncation ; the area beneath is more or less incurved, and the inferior 

 margin of the extremity, which is sharply rounded, is not quite vertically beneath the 

 prominence of the superior or dorsal portion of the extremity, but is slightly less pro- 

 minent and nearer the centre, and the general plane of truncation consequently trends 

 inwards. The comparatively broad actinal surface is more or less tumid along the 

 longitudinal line, the actinal plastron being cojivex. The peripetalous fasciole closely 

 embraces the ambulacral petals, entering deeply into the lateral interradia. The latero- 

 subanal fasciole is very high in position, passing with a convex curve at a high level, 

 almost into the interpetalous area of the lateral interradia. 



Remarks. Notwithstanding the scanty details enumerated above, they are sufficient 

 to indicate that the Schizaster in question is clearly distinct from any of the other 



2g2 



