22 THE ATLANTIC. [chap. i. 



teiina with one tootli ; a long central spine on the posterior 

 border of the dorsal shield, bnt no lateral spines ; length 60 mm. 

 A single specimen of this species occurred (Station LXXIIL). 

 On comparing the figures of these two species and of their ana- 

 tomical details with those of Lophogaster given by Sars, one is 

 struck by their great general similarity ; but there are charac- 

 ters presented by the new genus, particularly in connection wnth 

 the dorsal shield, which not only entirely separate it from Lo- 

 phogaster, but enlarge our views on the whole schizopod group. 

 In both species the shield is sculptured by ridges traversing it in 

 different directions, and in both there is a long spiny rostrum ; 

 but this shield is merely a soft duplicature of the skin con- 

 nected with the body only anteriorly, and leaving live thoracic 

 segments entirely free. In the structure of the shield and in 

 its mode of attachment, Gnatlwphaus'm has the greatest resem- 

 blance to Apus among all crustaceans, but it differs from it 

 widely in other respects. Nebalia is the only schizopod in 

 which the carapa'ce is not connected wnth the posterior thoracic 

 segments, but in that genus the form of the carapace is totally 

 different, and the genera are otherwise in no way nearly related. 

 Neither the antennae, nor the scales, nor the parts of the mouth, 

 present any marked differences from those of Lophoga8ter,v;\i\\ 

 the exception of the second maxillae. These, with nearly the 

 same form as in the Norwegian genus, bear a pair of accessory 

 eyes. Such eyes are well known at the base of the thoracic and 

 even of the abdominal limbs in the Euphausid^, a family with 

 which the LopHOGASTKiDiE have otherwise nothing in common, 

 but hitherto they have not been met with in any other animal 

 on any of the manducatory organs. 



Of the eight pairs of legs seven are ambulatory, only the first 

 pair is, as in Lopkogaster, transformed into maxillipeds. The 

 gills are arborescent, and attached to the bases of the legs. The 

 abdomen and its appendages scarcely differ from those of Lopho- 

 gaster. We find here also that the last segment is apparently 



