THE DEEP-SEA FAUNA. 457 



Twenty- six Echinideans were observed during the 

 * Lightning ' and ' Porcupine ' cruises off the coasts 

 of Britain and Portugal at depths ranging from 100 

 to 2.435 fathoms, at which latter depth the group 

 was represented by a small variety of Echinus vor- 

 reyicus, and a young example of JSrissopsis lyrifcra. 



Among the Cidaridgp, Cidaris papillate*, LESKE, 

 occurs in enormous numbers over hard ground, at 

 depths from 100 to 400 fathoms. This species has 

 a very wide range, inhabiting an apparently un- 

 broken belt from the North Cape to the Strait of 

 Gibraltar, and then passing into the Mediterranean. 

 This is a variable form, within narrow limits of 

 variation. The southern specimens gradually pass 

 into the form, it can scarcely be called a variety, 

 which is the type of Lamarck's species, C. hy strive. 

 Cidaris affiuls, PHILIPPI, is very common in the 

 Mediterranean, especially along the African coast. 

 I think this pretty little form must for the 

 present be considered distinct. The body spines 

 are bright scarlet, and the long spines, in marked 

 specimens, are brown banded with red or rose, so 

 that it is a singularly pretty object. 



The genus Porocidaris and the three species of the 

 family Echinothuridse, and their interesting relations 

 to fossil forms, have already been considered; but 

 even these are scarcely more suggestive of early 

 times than two genera of irregular urchins, one 

 dredged off the coast of Scotland, and the other at 

 the mouth of the English Channel, 



The first of these is Pourtalesia, one species of 

 which, P. jeffreysi, has already been figured and 

 described (p. 108), According to the classification of 



