304 U.S. NATIONAL MUSEUM BULLETIN 271 



Coxa 2 not concealing anteroventral corner of coxa 1 (fig. 117a), coxa 1 



normal and quadrate or distally expanded 8 



2. Coxa 1 half as long as its article 2 (fig. ISOk) 3 



Coxa 1 as long as or longer than its article 2 (fig. 130gr) 6 



3. Gnathopod 1 subchelate (often poorly) 4 



Gnathopod 1 simple 5 



4. Lobes of maxilla 2 equally broad or inner lobe narrower than outer, mandibu- 



lar molar short, blunt, or weakly laminate (fig. 126e), inner plate of maxilla 



1 with two setae Metambasia and Schisturella 



Inner lobe of maxilla 2 much broader than outer, mandibular molar conico- 

 laminate (fig. 126/), inner plate of maxilla 1 densely setose (4 or more 

 setae) Aristias 



5. Lobes of maxilla 2 not or scarcely gaping, inner not broader than outer. 



Metambasia 

 Lobes of maxilla 2 gaping (fig. 127 j), inner much broader than outer. 



Aristias 



6. Maxilliped: outer plate lacking spines Ambasiopsis 



Maxilliped: outer plate spinose 7 



7. Telson deeply cleft (three fourths or more), outer lobe of maxilla 1 poorly 



spinose (fig. 127c), inner ramus of uropod 2 simple Neoambasia 



Telson deeply cleft, outer lobe of maxilla 1 normally spinose, inner ramus of 



uropod 2 simple Tryphosella 



Telson cleft one third, outer lobe of maxilla 1 normally spinose, inner ramus 



of uropod 2 constricted Schisturella (=Pseudonesimus) 



8. Gnathopod 1 simple 9 



Gnathopod 1 subchelate 11 



9. Pereopod 5 much longer than pereopod 4 Ichnopus 



Pereopod 5 not longer than pereopod 4 10 



10. Inner ramus ot uropod 2 incised Socarnoides ' 



Inner ramus of uropod 2 simple. 



Waldeckia, Socarnes, and Socarnella (see Key P, couplet 20) 



11. Head lacking distinct lateral lobes, anterolateral cephplic margins straight 



(fig. 1216); coxa 5 as long as coxa 4 Lepidepecreoides 



Head bearing lateral lobes, anterolateral cephalic margins bulbous or convex; 

 coxa 5 shorter than coxa 4 12 



12. Article 4 of antenna 2 very tumid (fig. 124A;) Lysianella 



Article 4 of antenna 2 of normal dimensions 13 



13. Mandibular molar large but not strictly cuboidal, often subconical or 



attenuated or basally bulbous and covered densely with setules (fig. I267) 



14 



Mandibular molar large or of medium size, cuboidal, ridged, setules if rarely 



present very sparse (fig. 126g) 15 



14. Article 6 of gnathopod 1 enlarged (fig. 1290, telson apically notched . Koroga 

 Article 6 of gnathopod 1 not enlarged, telson deeply cleft Anonyx 



15. Uropod 2 with inner ramus strongly incised, epistome with extremely large, 



acute anterior process Tryphosites 



Uropod 2 with simple inner ramus, epistome unproduced. 



"Tmetonyx" nobilis (Stimpson) (see Shoemaker, 1930) and Hippomedon 

 Uropod 2 with inner ramus strongly incised, epistome and upper lip coalesced 



(not separated by notch from lateral view), apparent upper lip portion 



strongly produced and acute. 



"Tryphosa" carinata Schellenberg, 1926a 



1 And see "Tryphosa" carinata Schellenberg, 1926a (couplet 15) and Orchomene (p. 353). 



