64 FOREIGN OOLITIC CIDARID^E. 



D. Species from the Kimmeridge Clay. 



Cidaris Boloniensis, Wright, nov. sp., 1855. Figured in Mr. Davidson's MSS., pi. 1, 



figs. 11, 12. 



Form unknown, plates and spines only found. Ambulacra very narrow, with two rows 

 of small granules ; poriferous zones as wide as the areas ; pores oblong, separated by thick 

 septa ; inter-ambulacra wide, plates twice and a half as broad as they are deep ; areolas 

 elliptical, central, much excavated ; bosses small, summits broad and deeply crenulated ; 

 tubercles large, gradually increasing in size from below upwards ; scrobicular circle com- 

 plete in the upper areolas ; granules small, a little larger than those in the zone ; miliary 

 zone wide ; the granules diminish in size between the scrobicular circle and the centro- 

 sutural line ; a second miliary zone between the scrobicular circle and the poriferous zones. 

 Spines long, cylindrical, or a little compressed ; head very large ; rim of the acetabulum 

 deeply crenulated ; ring very prominent, forming a carina milled with microscopic lines ; 

 neck long, lower half covered with fine longitudinal lines, upper half smooth ; stem nearly 

 round, and closely covered with small granular longitudinal lines, compressed at the ex- 

 tremity ; arising, at irregular intervals, from among the granular lines, are a number of 

 short, stout, thorn-like, forward- directed prickles ; in some of the more spatulate varieties 

 of the spines the prickles are not conspicuous, but in the round forms they are very 

 prominent processes. 



M. Bouchard Chantereaux, of Boulogne, who kindly sent me the specimens, at the same 

 time states, " they are the only debris of the species that I have yet found. If we may 

 judge of the size of this urchin by the dimensions of the tubercular plates, this species 

 must have been at least four times larger than Hemicidaris Boloniensis, which you have 

 now." 



This Cidaris was most accurately figured in detail by my excellent friend Mr. 

 Davidson, in PL I of an ' Atlas of Plates illustrative of the Fossils of the Boulonnais,' and 

 which plates have been most obligingly placed at my disposal for this work. 



Formation. — Kimmeridge Clay, near Boulogne-sur-Mer. 



Collections. — M. Bouchard Chantereaux, Mr. Davidson, my Cabinet. 



