166 THE FOSSIL ECHINOIDEA 



similar band appears to have existed in the larger or type example, but owing to its state 

 of preservation it is impossible to say definitely. 



The periproct is transverse and subelliptical, equal in breadth to the transverse 

 diameter of the peristome (5-5 millim. in a specimen 39 millim. long) ; it is marginal 

 in position, and wholly visible when the posterior extremity of the test is placed in the 

 direct line of view. The character of this aspect of the test may be seen in Figs. 5 & 9. 

 It is probable that the great height of the periproct in the small specimen is in a certain 

 measure a premature character ; but we are unable to say to what extent it was main- 

 tained in the larger and more perfectly developed form. 



Young Forms. There are two small tests, one measuring 24 millim. in length 

 and the other slightly larger, which we regard as the young of this species. The pro- 

 minent characters which have led to this determination are the lanceolate form of the 

 petals, the tumid and raised interporiferous area, the tumid actinal surface, the distinctly 

 pentagonal peristome, the great height of the posterior portion of the test, and the 

 intra-marginal position of the periproct. 



The longitudinal profile of the dorsal surface of this small test corresponds exactly 

 with that of the adult form. The marginal contour is regularly oval, but is rather less 

 elongate than in the type. The actinal surface, though tumid, is scarcely as much so 

 as in the larger specimen ; and the same remark applies to the example 39 millim. in 

 length previously noticed. The ambulacral petals on the dorsal surface are distinctly 

 lanceolate in outline, contracting sensibly towards their outer extremity ; and the inter- 

 poriferous area is tumid. The poriferous zones are very unequal, the posterior zones 

 of the posterior petals being scarcely two thirds the length of the companion zone ; 

 and the anterior zones of the anterior petals are much shorter than their companions, 

 but the disparity is not as great as in the posterior petals. The peristome is large. and 

 distinctly pentagonal, the two ajiterior bourrelets are faintly developed, and the 

 character of a phyllode is already discernible from the size and disposition of the 

 ambulacral plates and pores, which occupy the region of its position, although the 

 secondary pores do not yet appear to be present. The periproct is large, entirely 

 removed from the actinal surface, and is placed very high in the posterior margin ; 

 when the profile of the test is seen from behind, the aperture appearing to occupy a 

 position nearly midway between the dorsal and ventral surface-lines. The posterior 

 odd interradium is faintly rostrate and faintly keeled along the median dorsal line ; 

 ventrally this area is more tumid than the others, but not in so great a degree as in 

 the more fully' developed tests. 



In the ornamentation of the test a number of the primary tubercles on the actinal 

 surface occupy an excentric position within their scrobicule, being close to the anterior 

 margin of the same. , 



MemarJcs. From the circumstance that this species has as yet only been found in 

 association with Echinolampas Sindensis, and from our ignorance of the characters of 

 the young tests of that species of corresponding size to the examples under notice, we felt 

 some hesitation in determining these small specimens. The characters above mentioned 

 appear sufficient, however, to justify the decision we have arrived at ; and that opinion 



