652 Jilicrojassa, Jassa 



Peraeopod 5 longer, 2'^ Joint widest at the middle. Branchial vesicles veiy 

 small. Marsupial plates rather large. Pleopods 1 — 3 with 2 coupliug spines,. 

 inner ramus with 5 — 7 joints, outer with 6 — 8. üropod 1, peduncle louger 

 than rami. Uropod 2, peduncle longer than outer, shorter than inner ramuB. 

 Uropod 3, peduncle stout, longer than peduncle of uropod 2; outer ramus 

 having on distal half about 9 miuute deuticles, encreasing towards apex; 

 inner ramus rather longer, sti-aight, tipped with spine. Telson triangulai", 

 as broad as long, with a setule on either side of rounded apex. Colour brown. 

 L. 3 mm. 



Firth of C]yde, depth 38 mm; Irish Sea (North Wales). 



4. Gen. Jassa Leach 



1813/14 Jassa (part.), Leach in: Edinb. Enc., v.l p. 433 | 1899 J., T. Stebbing^ 

 in: Ann. uat. Hist., ser. 7 v. 3 p. 239 | 1852 Cratophium, J. D. Dana in: Amer. J. Sei., 

 ser. 2 V. 14 p. 309 | 1853 C, J. D. Dana in: U. S. expl. Exp., v.l^n p. 832, 840. 



Body more slender in d than in o . Head with small rostral point 

 and lateral lobes somewhat produced. Side-plate 2 broader than deep in d; 

 3^ and 4*^ in both sexes deeper than 2'^ or 5*^; 4*^ not perceptibly emarginate 

 behind. Antennae 1 and 2 setose. peduncle long, flagellum much shorter. 

 Antenna 1, 1^* Joint shorter than 2^ or 3*^; accessoiy flagellum very small. 

 Antenna 2 usually considerably longer and stouter than antenna 1, especially 

 in <5 . Upper lip rounded, epistome (so far as known) with pointed process. 

 Lower lip normal. Mandible normal, palp very large, 3*^ Joint shorter than 

 2*^, distally widened, sti'ongly setose. Maxiila 1, inner plate very small 

 with inconspicuous marginal setae, outer plate with 9 apical spines; 2*1 Joint 

 of palp long, with apical spine-teeth. Maxiila 2, inner plate the shorter, 

 with lateral fringe. Maxillipeds normal, compact. Gnathopod 2 in both 

 sexes much larger than gnathopod 1, stronger in (S than in 9 ; the bind 

 margin of 6*^ Joint in d produced into a strong tooth. Peraeopods 1 

 and 2, 2^ Joint slightly expauded. Peraeopods 3 — 5 successively longer, 

 with moderately expanded 2*^ Joint. Uropods 1 and 2, outer ramus shorter 

 than inner, üropod 3, peduncle stout, much longer than the rami, out«r 

 of which ends in a hook or hooked spine and usually has little teeth on 

 the Upper margin, inner ramus sti-aight. Telson triangulär. 



7 species accepted, 4 obscure. 



Synopsis of accepted species: 



{Gnathopod 2 in cJ, finger with prominent tooth 

 on inner margia — 2. 

 Gnathopod 2 in (J, finger without prominent tooth 

 on inner margin — 3. 



{Gnathopod 2 in cj, 6th Joint with subbasal thick- 

 ended tooth 1. J. dentex . . . . p. 653 

 Gnathopod 2 in <5, 6th Joint with basal thin- 

 ended tooth 2. J. falcatiformis . p. 653 



{Gnathopod 2 in (5, Bth Joint with thumb-like 

 process near the base — 4. 

 Gnathopod 2 in c?, 6th Joint with thumb-like proces« 

 remote from base — 6. 



