MARINE GAMMARIDEAN AMPHIPODA 215 



articulate palp, molar triturative (except in a few genera) ; lower lip 

 with or without inner lobes; other mouthparts basic, except one genus 

 with shortened palp of maxilla 1; gnathopods either powerful and 

 subch elate, occasionally small, or feeble, occasionally nearly simple 

 (Harpinioidella) ; coxae of medium length or short ; uropod 3 with 

 elongate, lanceolate rami; telson often elongate, much longer than 

 peduncle of uropod 3, or increasingly shortened, cleft deeply or slightly 

 cleft only apically, occasionally appearing to be emarginate; in 

 Eusirogenes telson shorter than peduncle of uropod 3. 



Relationship. — The Astyridae differ from the Eusiridae by the 

 nontriturative mandibular molar and the characteristic shape of the 

 lower lip. Some astyrids have a massive head and all have a very 

 short telson. 



The Vitjazianidae are distinguished by their distinctly simple first 

 gnathopods and the elongate article 1 of the flagellum on antenna 1 

 which equals the peduncle in length. Pleustidae have their character- 

 istic lower lips. 



Since Calliopiidae appear to be Eusiridae-Pontogeneiidae with fused 

 telsonic lobes and some Eusiridae have nearly entire telsons, it must 

 be pointed out that Sancho in the Calliopiidae, with entire telson and 

 with 1-articulate accessory flagellum as long as article 1 of the primary 

 flagellum has gnathopod 2 similar to the ''Eusirus" gnathopods and 

 might be placed more logically in Eusiridae than in Calliopiidae. See 

 the latter family for further discussion. 



Most synopiids have a multiarticulate accessory flagellum but a few 

 have an accessory flagellum similar to that of eusirids. The massive, 

 galeate head of most synopiids is characteristic, especially because of 

 its strongly deflexed rostrum. Synopiid gnathopods are feeble whereas 

 those of eusirids are usually powerful. 



Rhachotropis aculeaia bears resemblance to Paramphithoidae in its 

 slightly acute first four coxae but differs by its powerful gnathopods. 

 Gnathopods of Paramphithoidae are feeble and one or more of the 

 first four coxae are acuminate. 



All Liljeborgiidae have a nontriturative mandibluar molar, but 

 eusirid resemblance to this family is close because some liljeborgiids 

 have a 2-articulate accessory flagellum and a few eusirid genera have a 

 poorly triturative mandibular molar. 



Most Gammaridae differ from Eusiridae by their multiarticulate 

 accessory flagella but a number of genera have 1-2-articulate accessory 

 flagella (see couplets 6-17 in Gammaridae key). Eusiridae differ from 

 those genera of Gammaridae by their elongate telsons and the slight 

 elongation of the metasome. Nearly half of those gammarid genera 

 have short inner rami on uropod 3, and most of the remainder have 

 either foliaceous rami on uropod 3, and elongate article 2 of the 



