THE ARTHROPOD A OF THE DEEP SEA 129 

 of 9 inches (fig. 15). Stenefoium haswelli, again, is 







larger than any of the shallow-water species of the 

 genus, and the same remark applies to the deep- 

 sea species of the genus Ichnosoma, while lolanthe 

 acanthonotus, from a depth of nearly 2,000 fathoms, 

 is considerably larger than most of the shallow-water 

 A-sellidae. 



There is another very common character of deep- 

 sea Crustacea that is also well exemplified in the 

 group of the Isopods, and that is the extraordinary 

 length and number of the spines covering the body. 

 I have already referred to this character in the 

 supposed deep-sea Copepod Pontostratiotes abyssicola, 

 and I shall have again to refer to it in treating of the 

 Decapoda and other groups of the Crustacea. 



Besides its enormous size Bathynomus possesses 



some other characters that may be correlated with 



its deep-sea environment. The respiratory organs are 



quite different from those of other Tsopods ; instead 



of being borne by the abdominal appendages, they 



are in the form of branched outgrowths from the 



body-wall containing numerous blood-lacunas, and 



the appendages simply act as opercula to cover and 



protect them. The eyes of the Bathynomus too are 



remarkably well developed, each one bearing 4,000 



