THE ARTHROPOD A OF THE DEEP SEA 135 



The pelagic Schizopoda are usually quite pale and 

 transparent ; the deep-sea forms on the other hand 

 are frequently if not invariably of a bright red colour, 

 as is the case with many other deep-sea Crustacea to 

 which reference will be made later on. 



Passing 011 to the group of the Decapoda, we find 

 that the most interesting of all the abysmal cray- 

 fish is the family of the Eryonidas ; indeed, in some 

 respects the discovery of these curious forms may be 

 reckoned among the most valuable results of the 

 1 Challenger ' Expedition. They are characterised by 

 the dorsal depression of the anterior part of the cepha- 

 lothorax, the absence of a rostrum, and the absence 

 or very rudimentary condition of the eyes (fig. 18). 



Their nearest relations seem to be certain genera 

 of Crustacea that are found in Jurassic strata, in the 

 lias, and more particularly in the lithographic slates 

 of Solenhofen. 



They have a very wide bathymetrical range ex- 

 tending from a depth of 250 fathoms (Polycheles 

 crudfera) to a depth of 2.000 fathoms (Wille- 

 moesia). 



But there are many other curious forms of the 

 macrurous Crustacea that deserve a passing men- 

 tion. The graceful Xematocareimis gracilipeSj distin- 



