12 



third and fourth pairs a Httle elongated with the distal setse peculiarly 

 developed. Exopod of uropods divided by a feeble articulation, its 

 proximal joint with several or at least a few spines but without 

 setae on the outer margin. (Telson entire). . . . Subfamily II. Siriellinse. 



,5. Labrum broader than long, without front process. Thoracic legs 

 with sixth joint divided by several vertical articulations and without 

 terminal brush; "claw" not developed. Pleopods well developed; 

 four posterior pairs with lamellar pseudobranchiae ; exopod of second 

 pair very elongated, while both rami are similar in the following 

 pairs. Both rami of the uropods divided beyond the middle by a 

 sharp articulation; outer margin of the proximal joint of the exopod 

 without spines, setose. (Telson entire) . . . Subfamily III. Rhopalophthalminae. 



Exopod of uropods undivided. 



a. Outer margin of the exopod of the uropods with a single spine or 

 with two or several spines but without setse between the spines 

 and the base. Labrum much longer than broad, with a very long 

 front process. Third pair of pleopods with the exopod elongated, 

 its endopod and the other pairs either well developed or reduced 

 in very varying degree. First abdominal segment in the female 

 always (?) with a pair of lateral lamellae. Endopod of the uropods 

 either overreaching the exopod or reaching its end. (Telson long as 

 compared with the exopod, distally cleft) . . . Subfamily IV. Gastrosaccinae. 



p. Outer margin of the exopod of the uropods without spines, but 

 with normal setse from the end to near the base. Labrum generally 

 broader than long, without front process, rarely either a little longer 

 than broad with a short process or quite anomalous. Fourth pair of 

 pleopods with the rami either similar and well developed or, generally, 

 with one of the rami — and most frequently the exopod — less 

 or more elongated, while the other ramus and both rami of second 

 and third pair are either well developed, normal, or less or more 

 reduced; in a few genera all pleopods are rudimentary. First abdo- 

 minal segment in the female without lateral lamellae. Endopod of 

 the uropods rarely reaching the end of the exopod, generally con- 

 spicuously or much shorter. 



f. Labrum of normal shape, rounded behind. Mandibles with the 

 cutting lobe not expanded and its edge dentate ; maxillulse of 

 the u.sual shape with oblique laciniae; maxillipeds with their sixth 

 joint normal, consequently without any free and aculeate ter- 

 minal margin Subfamily V. M y s i n ae. 



§. Sixth joint of thoracic legs generally with two articulations, the 

 proximal oblique, very rarely vertical {Arachnomysis Chun); 



