316 U.S. NATIONAL MUSEUM BULLETIN 271 



33. Maxillipedal palp with three articles (fig. 128j) Perrierella 



Maxillipedal palp with four articles 34 



34. Plates of maxilla 2 subequally broad and not gaping, article 1 of antenna 2 



very enlarged and subspherical (adults), telson elongate . . Eurythenes 



Inner plate of maxilla 2 much broader than outer, inner plate often strongly 



gaping mediad (fig. 127j), article 1 of antenna 2 normally small, telson 



not elongate Aristias 



35. Palp article 4 of maxilliped vestigial (fig. 128fc) Centromedon ^ 



Palp article 4 of maxilliped well developed and claw-like 36 



36. Inner plate of maxilla 1 with at least one large falcate seta (fig. 127d). 



Hirondellea * 

 Inner plate of maxilla 1 with normal setae 37 



37. Setae of maxilla 2 reduced to one-two and four per inner and outer lobes 



(fig. 127A;) Adeliella 



Setae of maxilla 2 numerous (7+ per lobe) 38 



38. Outer plate of maxilla 1 with spines reduced to five or fewer . . Neoambasia 

 Outer plate of maxilla 1 with seven or more spines 39 



39. Gnathopod 1 enlarged, article 5 very short and with small, narrow posterior 



lobe, article 6 expanding distally, very broad, palm transverse or nearly 



chelate (fig. 1290 Cheirimedon latimanus Sars, 1895 



Gnathopod 1 of normal size, article 5 rarely lobate, article 6 not expanding 

 distally even though palm rarely transverse 40 



40. Labrum with distinct lobe projecting in front of epistome (from lateral view) . 



Ambasiopsis 

 Labrum not dominating epistome 41 



41. "Head small" (fig. 1236), epistome and upper lip small, inconspicuous, 



neither dominant Uristes 



"Head large" (fig. 122d), prebuccal complex conspicuous, epistome usually 

 dominating upper lip Tryphosella 



42. Inner plate of maxilla 1 with eight or more setae lining medial edge. 



Paralicella 

 Inner plate of maxilla 1 with three or fewer setae 43 



43. Coxa 5 as long as 4 (fig. 1216) Lepidepecreoides 



Coxa 5 much shorter than 4 44 



44. Telson entire or cleft less than one eighth its length 45 



Telson cleft one eighth or more its length 47 



45. Outer ramus of uropod 3 uniarticulate Pseudambasia 



Outer ramus of uropod 3 biarticulate 46 



46. Labrum rounded anteriorly and scarcely produced beyond epistome, inner 



ramus of uropod 2 simple, article 6 of gnathopod 1 enlarged and stout, 



palm transverse (fig. 129a) Koroga 



Labral area of prebuccal complex acutely produced in front of epistomal 

 area, inner ramus of uropod 2 constricted, article 6 of gnathopod 1 slender, 

 palm obsolescent, oblique Paralysianopsis 



47. Palp article 4 of maxilliped very stout and subclavate, dactyl of gnathopod 1 



as short and stout as dactyl of gnathopod 2 Pseudoanonyx 



MaxiUipedal palp article 4 typically unguiform (fig. 128c) 48 



48. Epistome with acute anterior process dominating upper lip . . Tryphosites 

 Epistome flat or rounded anteriorly 49 



3 Compare Adeliella. 



* See note, Key N, couplet 23. 



