312 THE CRUSTACEA 



SUB-ORDER 2. Eeptantia, Boas (1880). 



Body not compressed, often depressed ; rostrum often absent, depressed 

 if present ; first abdominal somite distinctly smaller than the rest ; 

 antennules without stylocerite ; antennal scale generally small or absent ; 

 legs strong, the first pair usually, the others never, stouter than their 

 fellows, basipodite and ischiopodite almost always coalesced in the first 

 pair, generally also in the others, two fixed points in the carpo-propodal 

 articulation, exopodites never present, podobranchiae often on some of 

 the first four pairs ; male genital apertures on coxopodites or on sternum ; 

 pleopods often reduced or absent, not used for swimming. 



SECTION 1. PALINURA. 



Abdomen extended, well-armoured, with well-developed pleura and 

 broad tail-fan ; carapace fused at sides with epistome ; rostrum generally 

 small or absent; exopodites of maxillipeds with riagella directed forwards ; 

 third legs like the first, chelate or simple ; appendix interna present on 

 some pleopods, at least in female ; exopodites of uropods not distinctly 

 segmented ; branchiae numerous. 



TRIBE 1. ERYONIDEA. 



Antennae with exopodite, first segment not fused with epistome ; first 

 four pairs or all the legs chelate ; first pleopods present. 



Family ERYONIDAE. Polycheles, Heller ; Pentacheles, Spence Bate 

 (Fig. 162, p. 271); Eryon, Desmarest (Fossil) (Fig. 185, p. 308). 



TRIBE 2. SCYLLARIDEA. 



Antennae without exopodite, first segment fused with epistome ; 

 none of the legs chelate except sometimes the last pair in the female ; 

 first pleopods absent. 



Family PALINDRIDAE. Palinurus, Fabricius ; Linuparus, White ; 

 Palinurellus, von Martens. Family SCYLLARIDAE. Scyllarus, Fabricius ; 

 Ibacus, Leach ; Thenus, Leach. 



SECTION 2. ASTACURA. 



Abdomen as in Palinura ; carapace not fused at sides with epistome ; 

 rostrum well developed ; exopodites of maxillipeds as in Palinura ; first 

 three pairs of legs chelate ; no appendix interna on pleopods ; exopodites 

 of uropods divided by a suture ; branchiae numerous. 



TRIBE NEPHROPSIDEA. 



Family NEPHROPSIDAE. Nephrops, Leach ; Nepliropsis, Wood-Mason 

 (Fig. 161, p. 270); Homarus, H. Milne-Edwards. Family PARASTACIDAK. 

 Parastacus, Huxley ; Paranephrops, White. Family ASTACIDAE. Astacus, 

 Fabricius (Potamobius, Samouelle) ; Cambarus, Erichson. 



