REPORT ON THE ECHINOIDEA. 37 



known before, beyond the well-known differences between the spines near the actinos- 

 tome, the smooth spines near the abactinal system, and the typical primary coronal 

 spines covered with uniform granulation and serration, or the more or less distinct 

 fluting and serrations of the spines of Dorociduris. The discovery in the Caribbean Sea 

 of a species oi Dorocidaris {Dorocidaris hlakei, A. Agassiz), with flat fan-shaped radioles, 

 shows that we may expect, even in the genera of Cidaris with uniform radioles, an 

 amount of variation in the shape of the spines and their ornamentation fully as great 

 perhaps as that with which we are familiar in Rhcibdocidaris, Goniocidaris, and 

 the like. 



During the "Blake" expedition of 1878-79, a number of specimens of Dorocidaris 

 hlakii were collected from different localities. These are extremely interesting as 

 showing the gradual passage of a long cylindrical tapering radiole, either fluted or not, 

 with more or less prominent serrations, into a broad flat fan-shaped spine. The 

 detailed descriptions and figures of these spines will appear in the reports of the 

 " Blake " Echinids. 



Bahia, 7 to 20 fathoms. 



Fernando Noronha, shallow water. 



St Vincent, Cape Verde, 15 to 20 fathoms. April, 1873. 



Dorocidaris (Cidaris). 



Orthocidaris, A. Agassiz, 1863, non Cotteau. 



Dorocidaris, A. Agassiz, 1869, Bull. Miis. Comp. Zool., vol. i. 



^Dorocidaris (Cidaris) hracteata^ (PL I. fig. 1 ; PI. XLII. fig. 1). 



Dorocidaris hracteuta, A. Agassiz, 1879, Proc. Am. Acad., vol. xiv. p. 197. 



This species is the Pacific representative of Dorocidaris papillata, which has such a 

 wide range in the Atlantic. It is characterised by the small size of the papillae covering 

 the abactinal area, and the small size of the mammary boss of the primary tubercles, 

 their smaller number compared to specimens of Dorocidaris papillata of the same size, 

 the great size of the abactinal area, and the short slender papillae surrounding the base of 

 the primary spines. The primary radioles are long, pointed, slender, deeply fluted, the 

 fluted edges more or less serrated (PI. I. fig. 1). The serrations are frequently connected 

 into lamellae, or in other specimens, those from deeper stations, the serrations are largest 

 and most prominent on the lower third of the shaft ; they are very distinct, extending 

 over the whole surface of the spines, and the fluting is scarcely perceptible. The short 

 slender primary spines of the actinal surface are smooth, and strongly fluted. The largest 

 primary spines are twice the diameter of the test. In alcoholic specimens the papdlse of 

 the ambulacral, interambulacral, and abactinal areas are light reddish-brown, the spines 



' The genera and species first discovered by the Challenger are all marked with ;ui asterisk. 



