506 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxiii. 



g\ Mandibles with the distal part produced into a long prominent proc- 

 ess, the pair much overlapping; the secondary plate and molar eva- 

 nescent. First maxillee having the plate of the first joint unarmed, 

 of the third carrying one very long spine. Second maxillse small 

 and feeble, the free plates almost rudimentary, with few setfe. 

 Maxillipeds with the palp narrowed, not very setose. 



Family VI. Corallanidx (p. 517). 



/. Mandibles with the distal half narrow, most or all of it concealed by 



the upper and lower lips; from the base toward the apex directed 



gradually inward Family VII . Alcironidse (p. 519 ) . 



e^. Maxillipeds with the palp embracing the cone formed by the distal parts 

 of the mouth organs, the inner upper margin and apex never setose, 

 the apex and sometimes the inner ujjper margin, at least in the 

 males and in females without eggs, l^eing furnished with outward- 

 curved hooks. 

 /. Mandibles with the secondary plate very often visible; palp with no 

 inflated joint. Maxillipeds commonly seven-jointed, sometimes 

 four-jointed, the last joint in the latter case rather short, obtuse. 

 Antennae long, unequal, with well-defined peduncle and flagellum. 



Family VIII. .Egidie (p. 520). 

 f. Mandibles with no secondary jilate; the palp in adults with first joint 

 or both first and second joints inflated. Maxillipeds always four- 

 jointed, last joint rather long and narrow, subacute. Antennee much 

 reduced, without clear distinction between i)eduncle and flagellum. 



Family, IX. Cymotlwidx (jj. 525). 

 d'. Uropoda with one of the branches almost obsolete or rudimentary — not 



lamelliform Family X.' Limnoriidse (p. 532 ) . 



i/. Abdomen consisting of less than six segments. Abdomen with two segments. 

 Uropoda with one branch fixed, immovable. 



Family XI. SphseromMse (p. 532). 



Family III. GNATHIID^. 



11. GNATHIA Leach. 



ANALYTICAL KEY TO THE SPECIES OF GNATHIA. 



a. Mandibles in male with the basal part ornamented on the superior margin with an 

 elevated crest, which is irregularly dentate. Legs furnished with many 

 spiny processes 17. Gnathia eristata ( Hansen ) . 



a^. Mandibles in male without elevated crest on the superior margin. Legs witiiout 

 spiny processes. 

 b. Mandibles in male with slightnotch outside, inner edge obtusely produced in the 

 middle, tip acute, slightly incurved. Front of head not produced in the 



middle beyond the antero-lateral angles 18. Gnathia elongata (Kr0yer). 



I/. Mandibles in male carinate on outer side near the middle, the carina ending in 

 a tooth-like process, irregularly and bluntly toothed near the base within, 

 turned upward at apex. Front of head produced in the middle much beyond 

 the antero-lateral angles 19. Gnathia cerina ( Stimpsou) , 



17. GNATHIA CRISTATA (Hansen). 



Anceun cristaius Hansen, Vidensk. Meddel. naturh. Foren. i. Kjoebh., 1887, p. 182, 

 pi. VII, fig. 2-2a. 



Habitat.— I'P 32' lat. N., 58° 51' long. W. 

 Depth. — 116 fathoms. 



