REPORT ON THE SCHIZOPODA. 



29 



255 fathoms {Gnathojihausia longispina), the greatest 2200 fathoms {G nathophcmsia 

 gigcis). Gnatho2^hcmsia has never been taken at the surface of the sea, although the 

 surface-net was in frequent use during the Expedition, both by night and day, and in many 

 different tracts of the ocean. It may therefore certainly be assumed that these 

 Crustacea, notwithstanding their strongly developed natatory organs, never leave the 

 deeper strata of the sea, and that in all probability they have their habitat on the sea- 

 bottom itself. 



To judge from the inconsiderable number of examples of each species obtained by the 

 Expedition, notwithstanding that a large trawl-net was generally in use, it would appear 

 that the animals of this genus lead a comparatively isolated existence, being seldom met 

 with in shoals. 



Distribution. — The genus seems to exhibit a very extensive geographical distribution, 

 being most probably represented throughout the greater part of the ocean, excepting 

 perhaps the Arctic and Antarctic regions. Thus, as will be shown in the sequel, species of 

 this genus have Ijeen recorded both from the North and South Atlantic, from the Pacific, 

 and from the seas of the Indian Archipelago. The genus may even be reckoned 

 among the European fauna, one of its species {G nathophausia zo'ea) having been found by 

 the French expedition in the Bay of Biscay. 



Classification. — The species may be naturally classed within two or rather three 

 sections or subgenera, chiefly characterised by the form of the antennal scale, the presence 

 or absence of an exopodite on the maxillipeds, and finally by the form of the carapace. 



The following synopsis of the species may be here appended : — 



Antennal 

 scale 



very small, not 

 jointed, outer 

 margin serrate. 

 Rostrum 



Synopsis of the Species of Gnathophaxisia. 



short, indistinctly denticulate, .... 



{ slightly produced, 

 elongate. Infero-posterior ) 



corners of carapace '\ produced as long ser- 



I 



rate spines, 



large, of usual 

 form, jointed, 

 outer margin 

 terminating in 

 a strong spine. 

 Inferoposterior 

 corners of cara- 

 pace 



rounded 

 off. Dor- 

 sal spine 



compara- 

 tively short. 



Upper 

 lateral keel 



greatly pro- 

 duced. An- 

 tennal scale 

 with spine 

 of the outer 



distinct. 



Epimera 

 of the 

 caudal 



segments 



obsolete, 



sharply 

 pointed, 



obtuse, . 



of moderate size, 



greatly produced and 

 serrate on both 

 margins. 



produced into two distinct spines, 



G. ingens, Dohrn. 

 G. gi'jas, Sulim. 



G. calcarata, G. 0. Sars. 



G. teillemoem, G. 0. Sars. 

 G. affinis, G. 0. Sars. 



G. elegans, G. 0. Sars. 



G. zoea, Sulim. 



G. longispina, G. O. Sars. 

 G. gracilis, Suhni. 



