158 THE FOSSIL ECHINOIDEA 



ambulacra the poriferous zones are unequal, the posterior zone being longer by about 

 nine pairs of pores than its companion, and it is also more curved ; but this only 

 to a slight degree. The poriferous zones of the other petals are subequal. 



The poriferous zones are rather narrow, measuring 1'5 millim. at the widest part 

 and diminishing gradually towards the outer extremity, where they are little more than 

 half this breadth. Near the apex the pores are unusually small, and, in the specimen 

 under description, a number of the pairs of pores are aborted near the apex. The 

 inner pores are round, the outer transversely elongate, and they are united by a broad 

 groove. The intervening costse are low, narrow, and are ornamented with a single line 

 of about six well-defined granules. The positions of the pairs of pores and of the costee 

 are rather oblique in relation to the median line of the petal, and the obliquity 

 increases as they approach the outer extremity. The extra-petalous continuations of 

 the poriferous zones are situated in very slight channels. The width of the inter- 

 poriferous area at the widest part of the postero-lateral petal is 4 millim., and it is only 

 a shade narrower than this at the outer extremity ; towards the apex the areas are 

 narrow and attenuate, and resemble E. subconica, nobis, in not expanding rapidly into 

 the petaloid form so frequent in this genus. The interporiferous areas are flush with the 

 test, or only so faintly tumid that the character is scarcely noticeable. The odd posterior 

 interradium is very full and tumidly convex, with a tendency to become subcarinate at 

 the apical extremity ; there is also a slight tendency, but much more feebly exhibited, 

 in the other interradia (especially the laterals) to become a little prominent near the 

 apex, which produces the appearance of the ambulacra being slightly sunken there. 

 The lateral and anterior interradia do not present any conspicuous tumidity, and the 

 test, as a whole, is gradually reduced in capacity towards the anterior extremity. The 

 ornamentation of the interporiferous areas is similar in character to that of the inter- 

 radia, excepting that the primary tubercles are somewhat more regular in position 

 and more closely crowded. Throughout the test the scrobicules are closely placed, the 

 intermediate spaces being seldom occupied by more than the single circlet of com- 

 paratively large, well-spaced miliary granules, which surround the scrobicules. The 

 ornamentation is most crowded just below the ambitus, the intermediate spaces between 

 the scrobicules being reduced to simple septum-like structures. The ornamentation of 

 this species seems to stand intermediate between that of E. subconica and that of the 

 ordinary EcMnolampas type. 



The whole of the central portion of the actinal surface is obscured by matrix, 

 which renders any observations on the peristome and neighbouring portions of the test 

 impossible. 



The periproct is situated in the actinal portion of the tumid curve of the margin, 

 and is consequently truly marginal. Its shape is transversely oval, and the greater and 

 less diameters are not more than 9 and 7 millim. respectively ; but, owing to fracture, 

 the exact measures cannot be given. 



The test subjacent to the adoral margin of the periproct shows traces of some 

 tumidity, and there is a slight bevelling of the test towards the aperture on that 

 jnargin. 



