10 THE VOYAGE OF H.M.S. CHALLENGER. 



DEFINITIONS OF THE FAMILIES. 



The four families of Scliizopoda above meutioued may be briefly characterised as 

 follows : — 



1. LOPHOGASTRID^. 



Carapace rather large, more or less calcareous ; its posterior part but loosely covering 

 the trunk, all segments of which are well defined dorsally. Maxillipeds robust, with the 

 exopodite imperfectly developed, the epipodite very large and projecting within the 

 branchial cavity. First pair of legs more or less distinctly modified as guathopoda, 

 remaining pairs uniform and ambulatory, with well-marked dactylus. Branchiae (arthro- 

 branchise) very complex, arborescent, consisting of three or four principal branches, the 

 innermost largest and freely projecting beneath the trunk, the remaining branches covered 

 by the carapace, posterior pair rudimentary or wanting. Marsupium in female composed 

 of seven pairs of incubatory plates. Caudal limbs well develoj)ed in both sexes and 

 of uniform structure, natatory. Development without any free metamorphosis. 



Genera. 



\. Lophogaster, M. Sars. 

 2. Ceratolepis, G. O. Sars. 



3. Gnathophausia, Suhm. 



4. Chalaraspis, Sulim (ex parte). 



2. EUCOPIID.E. 



Carapace very large, membranous, the lateral wings produced and projecting over the 

 base of the tail. Segments of trunk all well defined. Maxillipeds nearly the same as in 

 the Lophogastridae. Legs dissimilar in structure, the three anterior pairs modified to 

 serve as gnathopoda, the three succeeding pairs extremely slender, filiform, with the 

 dactylus falciform and very mobile, last pair simple, not prehensile. Branchiae, 

 marsupium, and caudal limbs nearly the same as in the Lophogastridse. Development ? 



Genus. 

 Eucopia, Dana. 



3. EUPHAUSIID^. 



Carapace rather small, not calcareous, firmly connected with the trunk along the dorsal 

 face, leaving only part of the last segment closed above. Maxillipeds elongate, pedi- 

 form, with the exopodite well developed, natatory, the epipodite rudimentary or w^anting. 



