298 U.S. NATIONAL MUSEUM BULLETIN 271 



2. Coxa 1 half as long as coxa 2 (fig. 123a), palp of maxilla 1 very short (fig. 



127c) ; Trischizostoma 



Coxa 1 nearly as long as coxa 2, palp of maxilla 1 normal .... Normanion 



3. Uropod 3 biramous 4 



Uropod 3 not biramous, rami often obsolete 8 



4. Maxilla 1 : palp well developed, 2-articulate 5 



Maxilla 1: palp vestigial (fig. 127sf) Acidostoma 



5. Maxilliped: article 4 of palp well developed 6 



Maxilliped: article 4 of palp vestigial (fig. 128d) 7 



6. Telson deeply cleft, gnathopod 1 stout Shackletonia 



Telson entire, gnathopod 1 very slender, flagellate Azotostoma 



7. Gnathopod 1 simple Phoxostoma 



Gnathopod 1 strongly subchelate Normanion 



8. Gnathopod 1 simple 9 



Gnathopod 1 chelate Derjugiana 



9. Dactyl of gnathopod 2 present 10 



Dactyl of gnathopod 2 absent Ocosingo 



10. Coxae 1-2 strongly reduced in size and partially hidden by large coxa 3. 



Lepidepecreella 

 Coxae 1-2 large and visible Acontiostoma and Stomacontion 



1 See also Parawaldeckia kidderi (Smith) (p. 357). 



KEY C 



The first gnathopods of Valettia, Normanion, Cheirimedon and occa- 

 sionally of Orchomene and Hirondellea and females of Onesimoides are 

 weakly chelate. These genera are also included in other keys. Gnatho- 

 pod 1 of Microlysias is vaguely chelate but the genus is not included 

 here. 



1. Uropod 3 lacking rami Derjugiana 



Uropod 3 with rami 2 



2. Mandible: cutting edge sharply toothed (though often minutely) (fig. 



126o) 3 



Mandible: cutting edge not toothed (fig. 126h) 5 



3. Pereopod 3: article 2 deeply indentured (fig. 1316) Podoprion 



Pereopod 3: article 2 not indentured 4 



4. Inner ramus of uropod 3 vestigial, telson entire Onesimoides 



Rami of uropod 3 subequal to each other, telson cleft Valettia 



5. Maxillipedal palp 3-articulate (fig. 128g) 6 



Maxillipedal palp 4-articulate 9 



6. Telson cleft Podoprlonides 



Telson entire 7 



7. Maxilla 1 lacking palp Prachynella 



Maxilla 1 bearing palp 8 



8. Pereopods 3-5 : article 2 strongly indentured; palp of maxilliped not exceeding 



end of outer plate Podoprionella 



Pereopods 3-5: article 2 not indentured; palp of maxilliped shorter than 

 outer plate (fig. 128^) Normanion 



9. Coxa 1 reduced in size or tapering distally and partially hidden by coxa 2 . 10 

 Coxa 1 of normal size and subquadrate shape, and not hidden by coxa 2 . 14 



