MARINE GAMMARIDEAN AMPHIPODA 173 



4. Outer ramus of uropod 3 half or less as long as inner ramus . Leptamphopus ^ 

 Outer ramus of uropod 3 three fourths or more as long as inner ramus. 



Bouvierella ^ 



5. Lower lip with inner lobes (fig. 7 Id) 6 



Lower lip lacking inner lobes (fig. 71e) 14 



6. Article 5 of gnathopods with distinct posterior lobe (fig. 72n) 7 



Article 5 of gnathopods without distinct posterior lobe (fig. 72z) ... 10 



7. Article 6 of gnathopods slender, bent distally (fig. 72o), essentially simple, 



mandibular molar nontriturative Harpinioides 



Article 6 of gnathopods stout, not bent, mandibular molar triturative . . 8 



8. Body dorsally processiferous, pereopod 5 greatly elongate, article 5 as long as 



articles 2, 3, 4, and 6 together Stenopleuroides 



Body dorsally smooth or without sharp processes, pereopod 5 slightly longer 

 than 4, article 5 not disproportionately elongate 9 



9. Antenna 1 longer than or equal to antenna 2, telson apically notched or 



pointed (fig. 72/) Stenopleura ^ 



Antenna 2 slightly longer than 1, telson apically rounded (fig. 72d). 



Calliopius 



10. Gnathopods bearing grossly distinct palms (fig. 72m) 11 



Gnathopods not bearing distinct palms, essentially simple (fig. 72{) . . 13 



11. Articulate accessory flagellum present Atylopsis ^ 



Accessory flagellum absent, occasionally represented by process .... 12 



12. Coxa 4 slightly longer than coxa 1 (fig. 71a) . . Halirages and Apherusa ^ 

 Coxa 4 not longer than coxa 1 (fig. 716) Haliragoides 



13. Article 5 of gnathopods much longer than 6 (fig. 73d) .... Cleippides 

 Articles 5 and 6 of gnathopods subequal in length (fig. 72i) . . . Regalia 



14. Palp of maxilla 1 reduced, reaching only halfway along outer plate (fig. 71j)- 



Laothoes 



Palp of maxilla 1 of normal length, reaching to or exceeding apex of outer 



plate (fig. 710 15 



15. Dactyls of pereopods pectinate (fig. 72b) Metaleptamphopus 



Dactyls of pereopods weakly serrate or smooth but not pectinate ... 16 



16. Gnathopod 2 of the Eusirus kind, a large suboval sixth article attached to a 



slender fifth article (fig. 73a), (body and head extremely flattened). 



Sancho 

 Gnathopod 2 not of the Eusirus kind 17 



17. Accessory flagellum as long as article 1 of primary flagellum (body mod- 



erately depressed) Amphithopsis 



Accessory flagellum scale-like or absent 18 



18. Article 2 of pereopods 1 and 2 smooth anteriorly, body compressed lat- 



erally 19 



Article 2 of pereopods 1 and 2 with anterior process, body extremely flattened. 



Chosroes 



• B6Q2l\&o Atylopsis megalops'^whoWs (1938); and a few species of ylp/ierusa, Halirages, and Laothoes. Except 

 for^. megalops, none of these species has article 6 of the gnathopods more than 60% as long as article 2. Lao- 

 thoes is characterized by the condition of maxilla 1 palp. 



2 Pontogeneoides (Eusiridae) resembles Atylopsis but has an especially elongate telson; it also Iceys to 

 Stenopleura but has powerfully subchelate gnathopods like Eusiroides, large coxae and elongate telson. 



2 A few species of Rhachotropis (Eusiridae) may be keyed to this point because of obsolescent telsonic 

 clefts but they may be distinguished by their extremely elongate telsons being more than twice as long as 

 the peduncle of uropod 3. 



