CRETACEOUS ECHINODERMATA. 339 
5. Cidaris Bowerbankii, sp. nov. (Tab. XXIX. fig. 4.) 
The body of this Cidaris, which is very nearly allied to C. clavigera, is a de- 
pressed spheroid, more compressed above and below than in that species. The 
ambulacral segments are slightly broader in proportion to the interambulacrals, 
and instead of their breadth being occupied by transverse series of about four 
granular tubercles, two of which are very small and inconspicuous, there are 
four, or centrally, even six nearly equal granular tubercles in each transverse 
row. The large spinigerous tubercles of the ambulacral plates are placed in 
areole, much smaller in proportion to the entire body than in elavigera, and the 
tubercles themselves are also smaller. The spaces between the rows of spini- 
gerous tubercles are wider ; they are thickly studded with nearly equal granules. 
The spines are similar in shape to those of clavigera, though rather more in- 
versely conical, and none of them appear to have long stems. Their surface is 
minutely granulated with small spinous points which are arranged in irregular 
rows. 
The specimen figured is in the cabinet of Mr. Bowerbank, and came from the 
grey chalk of Dover. 
6. Cidaris perornata, nov. sp. E. F. White chalk. (Tab. XXV. fig. 8.) 
Body melon-shaped. Ambulacral plates large, seven or eight in a row, each 
bearing a spiniferous tubercle, in the midst of a very large area, the margins 
granulated and the edges bordered with small moniliform granules, the sutures 
depressed. Pores of the ambulacral avenues about fifteen to each central plate. 
Avenues about one-third the breadth of the ambulacra, which are sutured and 
ornamented with a triple series of depressed granules twice repeated, and very 
small intermediate ones. 
Spines long, cylindrical, several-ridged ; ridges irregular towards the base, ser- 
rated, their interstices granulated. 
A very beautiful and large species, reminding us of the oolitic C. maximus. 
7. Spine of a distinct species, of which the body is unknown. (Tab. XXIV. 
fig. 8.) 
8. A spine possibly also belonging to a distinct species. (Tab. XXIV. fig. 25.) 
