MARINE GAMMARIDEAN AMPHIPODA 161 



only by the peculiar lower lip. That this character is sufficient to 

 remove Astyridae from Paramphithoidae is doubtful, especially 

 because of the subacuminate condition of coxae 2 and 4 in astyrids 

 and the distally expanded and rounded-quadrate coxa 1 of Eclysis. 



The Laphystiopsidae lack an accessory flagellum, have normal 

 lower lips, and entire telsons. 



The Haustoriidae do not have the characteristic astyrid lower lip 

 and have fossorial (spiny and setose) pereopods 3-5. 



Astyroides Birstein and Vinogradova is synonymized with Alex- 

 andrella in the Stilipedidae. Stilipedids differ from. Astyra in the absence 

 of a mandibular molar, the broadening of the mandibular body, 

 the greater foliaceousness of the maxillae, but the two families are 

 strongly related by the condition of coxae 1-2, of which coxa 1 is 

 broader than 2 and 2 tends to taper distally. Stilipes stands between 

 Astyra and Alexandrella in the condition of its upper lip. 



Key to the Genera of Astyridae 



1. Coxa 1 subacuminate [Epimeriella] ' 



Coxa 1 rounded-subquadrate distally 2 



2. Accessory flagellum present Astyra 



Accessory flagellum absent [Eclysis] ^ 



1 See these genera in the Paramphithoidae (pp. 394, 395). 



Genera of Astyridae 



Astyra Boeck 



Astyra Boeck, 1871.— Stebbing, 1906. 

 Chagosia Walker, 1909. 

 Parastyra Pirlot, 1934. 



Type-species: A. abyssi Boeck, 1871 (monotypy). See Sars, 

 1895. 

 Species: 5, cosmopolitan, bathypelagic (100-2000 m). 



Atylidae 



Figures 67, 68 



Diagnosis. — Accessory flagellum vestigial or absent; urosomites 

 2-3 coalesced. Monogeneric. See Ampeliscidae, Dexaminidae, Pro- 

 phliantidae, Lepechinellidae. 



Description. — Accessory flagellum vestigial, 1-articulate or absent; 

 body with dorsal carinae or teeth; rostrum prominent; urosomites 



