Decajjod Crustacea of the North Atlantic. 191 



inhabiting- species, and their absence from the trawl when 

 coming from moderate depths, as shown in the records of their 

 capture, helps to confirm this. The small number and great 

 size of the eggs of A. gracilis would seem to indicate an 

 abyssal habitat for that species also ; but the large black 

 eyes are probable evidence that it does not descend to the 

 extreme depths inhabited by A. microphthalma. 



Their similarity of structure makes it probable that the 

 species of Oplophorus^ Ephyrina, Notostomus^ Meningodora^ 

 and Hymenodora are similar in habits to the species of Acan- 

 tkephyi^a, and the structure of their eyes and integument, and 

 the small number and great size of the eggs in the species in 

 which they are known, as well as the records of their capture, 

 indicate that they are all abyssal or at least deep-water species. 



The form of the body and the structure of the perajopods of 

 Pasiphae princeps indicate that, like the other species of the 

 genus, it is a free-swimming species, probably never resting 

 on the bottom. It is probably neither a truly abyssal nor, 

 judging from the size of the eggs as well as the records of its 

 capture, a surface species. The structure of the eyes, the 

 very small number and great size of the eggs, and the soft 

 integument of the species of Farapasiphae^ render it probable 

 that they are really abyssal species, though probably not con- 

 fined to the immediate region of the bottom. 



The eight species of Penaiidaj in the list are undoubtedly all 

 free-swimming forms not confined to the immediate region of 

 the bottom ; but, judging from the relatively small size of the 

 eyes and the presence of well-developed ocular papilla?, they 

 are all deep-water if not abyssal species. 



The records of occurrence of the three species of Sergestes 

 show that they are not confined to abyssal depths. The 

 relatively small eyes and exceedingly soft integument of S. 

 mollis would seem to indicate that it inhabited much greater 

 depths than the other species 5 but the records of its capture 

 afford no additional evidence of this. 



We may then divide these species provisionally into the 

 four following classes : — 



I. Sjjecies inhabiting the Bottom or its immediate 

 Neighhourhood. 



Geryou c[uinquedens. Mimidopsis similis. 



Ethusiiia abyssicola. Bairdii. 



Lithodes Agassizii. rostrata, 



Parap.igurus pilosimaniis. Pentacheles scupltus. 



Mimidopsis curvirostra. nanus. 



crassa. debilis. 



14* 



