GAMMARIDEA. 9Q9 



Subfam. 3. LEUCOTHOIN^E. — Antennae superiores basi plus mi- 

 nusve graciles. Maxillipedes elongati, angusti, articulo longo un- 

 guiformi confecti, lamellis intemis perbrevibus. Mandibular sive 

 palpigerae sive non palpigerse, processu molari carentes. [An sem- 

 per ?] Epimerse magnse. 



G-. 1. Stenothoe, Dana. — Epimerse permagnae, 4tae maximae, 5tae parvulae. 

 Pedes 4 antici subchelati, 2dis validioribus. Antennae superiores longiores, non 

 appendiculatae. Mandibulae non palpigerce, processu molari carentes. Styli 

 caudales lmi 2dique ramis bene subulati, 3tii simplicissimi, subulati, spina 

 crassa confecti. 



G-. 2. Leucothoe, Leach .*— Epimerae magnae, 5tae parvulae. Pedes 4 antici sub- 

 chelati, 2dis validioribus. Antennas superiores longiores, non appendiculatae. 

 Mandibulae palpigerae. Styli caudales toti biramei, ramis subulatis. 



[Cujus sedis est Microcheles, Kroyer,f Amphithoe affinis, cui mandibulae processu mo- 

 lari carentes : quoque Amphithoe Marionis, Edw., cui mandibulae non palpigerae.] 



Subfam. 4. GAMMARIN.^.— Antennse lmas basi graciles. Maxilli- 

 pedes sat lati, lamellis internis sat elongatis. Mandibular acie den- 

 ticulata instructs et altera accessoria quoque processu molari et 

 palpo 3-articulato. Pedes 10 postici non subprehensiles. 



A. Frons productus et infra antenntgerus non est, antennis Imis 



INFERIORIBU& NON ANTERIORIBUS. 



1. Styli caudales postici biramei, ramis subsequis. 



A. Pedes 2di non subchelati. 



Gr. 1. Acanthonotus, Owen. — Antennae quatuor subaequae, lmae non appendicu- 

 latae. Epimerae magnae. Pedes 2di filiformes, manu omnino carentes, lmi 

 manu vis confecti. 



Gr. 2. Alibrotus, Edw. — Antennae lmae breves, appendiculatae. Epimerae magnae. 

 Pedes lmi validi, non subchelati. 



* Kroyer states that the bi-articulate finger of Leucothoe is not a true generic charac- 

 teristic, and adds two species to the genus, one of which has this character imperfectly, 

 and the other not at all (Nat. Tids., iv. 141, 1842, and [2], i. 539, 1845). This cha- 

 racter of the hand depends mainly on the prolongation of the inferior apex of the ante- 

 penult joint, which prolongation is variously developed in species of allied genera. 

 They agree with Leucothoe in their peculiar slender maxillipeds; in the very small epi- 

 merals to the first segment, large fourth, and small fifth, sixth, and seventh; in the 

 caudal stylets; the very short third joint of the superior antennae, and other characters. 



f Tids. [2], ii. 5. 



228 



