MARINE GAMMARIDEAN AMPHIPODA 159 



Genera of Argissidae 



Argissa Boeck 



Argissa Boeck, 1871.— Stebbing, 1906. 

 Chimaeropsis Meinert, 1890 (homonym, Pisces). 



Type-species: Syrrhoe hamatipes Norman, 1869a (monotypy and 

 subsequent synonymy). See Sars, 1895. 



Species: 2 (possibly synonymous), N. Hemisphere and possibly 

 cosmopolitan, eurybathic (30-1919 m). 



Astyridae 



Figure 66 



Diagnosis. — Accessory flagellum 1- or 2-articulate, slender (or 

 absent in dubious genera) ; mandibular molar nontriturative ; lower 

 lip with outer lobes very widely separated; gnathopods feeble. Mono- 

 generic. See Eusiridae, CaUiopiidae, Pleustidae, Liljeborgiidae, 

 Haustoriidae, Synopiidae, Vitjazianidae, Hyperiopsidae, Paramphi- 

 thoidae, Stilipedidae. 



Description. — Accessory flagellum a single, medium-sized article 

 or 2-articulate; body smooth; rostrum inconspicuous, head usually 

 normal in appearance but occasionally massive and with "shark nose" 

 appearance (as in some Synopiidae [=Tironidae] and some Par- 

 daliscidae) ; coxae of medium size or long, rounded or quadrate below 

 but 2 and 4 occasionally subacuminate; mandibular molar a conical, 

 setose, nontriturative lamina; outer lobes of lower lip very widely 

 separated, with or without small erect inner lobes; remainder of 

 mouthparts basic, occasionally maxillae subfoliaceous; gnathopods 

 feeble, barely subchelate; rami of uropod 3 very elongate; telson 

 short, entire or cleft. 



Relationship. — Usually, the Synopiidae strongly differ from the 

 Astyridae only by their multiarticulate accessory flagella (except the 

 genus Jeddo). The combination of very broadly separated lobes of 

 the lower lip, the fact that coxa 4 is usually larger than coxa 3 and 

 the peculiar, sharp, conical, nontriturative molar serve to distinguish 

 Astyridae. 



The short coxae and the absence of a mandibular molar distinguish 

 the Pardaliscidae. 



Oedicerotidae have strongly setose pereopods, lack an accessory 

 flagellum, have relatively short rami and therefore a relatively long 

 peduncle of uropod 3 and a non-astyrid lower lip. 



Most Eusiridae have either a ridged mandibular molar, do not bear 



