178 THE FOSSIL ECHINOIDEA 



poriferous areas are rather less than twice the width of the poriferous zone in the 

 posterior pair of petals, but are rather more than twice the width of the poriferous 

 zone in the anterior pair of petals. 



The peristome, though excentric in front, is nearer to the centre than the apical 

 disk ; it is large, transverse, and pentagonal, the transverse diameter being twice that of 

 the longitudinal diameter. There is a faint tendency towards thickening at the 

 margin, but bourrelets are not developed. In the ambulacral areas the peristomial 

 plates exhibit conspicuously the companion pair of buccal pores ; and the poriferous 

 zones in the vicinity of the peristome present a few well-defined pores, some of which 

 are internal to, and alternating with, the main series, and suggest the rudiments of an 

 incipient phyllode. 



The periproct is large and elliptical, placed longitudinally at the summit of the 

 posterior rostration, of which it occupies a large portion of the surface. The length 

 of the aperture is nearly twice the measure of its transverse diameter. The inferior 

 margin of the posterior rostration is full and well-rounded ; and a more or less tumid 

 development at the margin on either side the median line gives emphasis to a slight 

 depression beneath the periproct. Actinally the odd posterior interambulacrum is tumid 

 near the margin, a character which gradually diminishes towards the peristome. 



The ornamentation of the test is almost entirely destroyed ; from what remains it 

 appears to have been small, crowded, and very uniform throughout. 



Remarks. It is not without much hesitation that we have given a name to this 

 solitary and badly preserved specimen. In many respects it resembles in a remarkable 

 manner Ilarionia Sindensis, which in the characters of the ambulacral rosette it may 

 almost be said to mimic. The depressed and differently shaped test, the characters of 

 the peristome, of the incipient phyllodes, and of the actinal surface generally are 

 quite distinct and unconformable with Ilarionia. The species under notice constitutes, 

 however, a striking link between that genus and EcJiinanthus. 



Dimensions. 



millim. 



Length of the test 30 



Breadth of the test 24'5 



Height of the test 13 



Locality. In the Khirthar series of strata : — Baili, west of Tong. Survey-number 



a 304 

 23 • 



Illustrations of the Species in Plate XXXII. 



Fig. 4. Abactinal view of the test : natural size. 



5. Actinal view of the test : natural size. 



6. Longitudinal profile of the test: natural size. 



7. Transverse profile, seen from behind : natural size. 



8. The peristome and surrounding portions of the test : magnified. 



