some Species referred lo it. 57 



imperforate, rounded eminences, varying in size, and the 

 larger of them apparently mamelonate («. e. tubercles). 

 From 5 to 7 of them border one side of a larger scrobicnle, 

 and the same number its other side. The larger scrobicules 

 aie usually separated by a single line of about 3 to 5 

 miliaries (or possibly tubercles). 



As regards the radioles, I have nothing to add to the 

 accounts of Kolesch, Spandel, and Hesse (PI. I. fig. 7). 



Most of the writers who have dealt with Cidaris keyser- 

 Ungi have discussed its relations to C verneuiliana (King). 

 Wliile King, Geinitz, and Spandel have regarded them as a 

 single species, Desor and Kolesch have separated them, 

 though admitting their close relationship; but it has been 

 reserved for Lambert (1899, 1900) to place them in two 

 distinct genera — Eotiaris and Permocidaris. 



How far any of these writers have based remarks on a 

 study of actual specimens of the two species, they have not 

 told us. The following remarks are based on the specimens 

 of Cidaris keyserlingi in the British Museum, which have 

 just been described, and on a large series of specimens of 

 Cidaris verneuiliana horaTvins,idi\[ Hill now preserved in the 

 Hancock Museum, Newcastle-on-Tyne, and kindly lent me 

 by the Natural History Society of Northumberland, Durham, 

 and Newcastle-upon-Tyne. Unfortunately the originals of 

 King-'s figures (1850, pi. vi. ff. 22-2-4) are not among these 

 specimens, and Mr. E. Leonard Gill, the curator of the 

 Hancock Museum, has not been able to find them. There 

 can, however, be no doubt as to the specific identity of the 

 interambulacrals with those originally described (1818) and 

 subsequently figured by King. 



Tiie differences that Desor thought couhl ba seen in 

 C. verneuiliana were the more granular interradial tract, the 

 more complete scrobicular rings, and the radiating folds around 

 the base of the mamelon. These differences are clearly shown 

 in his figures; but in them certain small details of the 

 original figures have been grossly exaggerated. It should be 

 quite clear from the precednig description that the interradial 

 tract is quite as closely crowded with miliaries or with small 

 tubercles (the granules of Desor), and the scrobicular ring is 

 often quite as complete, in Cidaris keyserlingi as in any 

 specimen of C. verneuiliana. This was admitted by Kolesch, 

 who, however, still maintained that, "die radiaren Vertie- 

 fungen, welche sich an der Warzenbasis von Eocidaris 

 verneuiliana befinden, charakterisieren den letzteren als hi- 

 sondere Spezies'' (p. 661). Now it is a little difficult to 

 understand what Desor and Kolesch meant by these "plis 



