NO. 5 BARNARD: AMPHIPODA 73 



palp attached level with molar, article 3 about 70 percent as long as ar- 

 ticle 2 ; inner plate of maxilla 1 with 2 apical setae, outer plate with 

 long, well-developed spines; lobes of maxilla 2 not gaping, similar in 

 shape ; outer plate of maxilliped with small, imbedded medial spines, 

 apex with 2 large spines; gnathopods 1 and 2 with transverse palms; 

 coxa 1 not greatly shortened, triangular, as long as article 2 of 

 gnathopod 1, partially hidden by coxa 2; inner ramus of uropod 2 in- 

 cised ; uropod 3 with biarticulate outer ramus ; telson cleft halfway. 



Type species : Thro7nbasia tracalero, new species. 



Relationship: According to the review of ambasia genera by Dahl 

 (1959), this genus comes close to Neoambasia Dahl (1959) (type 

 Ambasiopsis tumicornis Nicholls 1938) ; but considering the degree to 

 which ambasia genera have been fragmented and the numerous weakly 

 developed characters distinguishing the present species from N. tumi- 

 cornis, it becomes necessary to erect still another monotypic genus to re- 

 ceive it. From Neoambasia the new genus differs in the much more 

 strongly produced upper lip, the elongated basal articles on both flagella 

 of antenna 1, the weakly developed mandibular molar, the well-devel- 

 oped spines on the outer plate of maxilla 1, and the constriction on the 

 inner ramus of uropod 2. The long first coxa distinguishes the genus 

 from Ambasia, Schisturella, and Metambasia; the subchelate first 

 gnathopod, produced labrum and mandibular palp location distinguish 

 it from Ambasiella; the presence of spines on the outer plate of the 

 maxilliped and the weak mandibular molar distinguish the genus from 

 Ambasiopsis. 



Thrombasia tracalero, new species 



(Figs. 23, 24) 



Diagnosis: With the characters of the genus. 



Description: Eyes absent; lateral cephalic lobes stongly projecting 

 and subacute; second pleonal epimeron slightly produced at posteroven- 

 tral corner ; third pleonal epimeron with large but not elongated pos- 

 terior tooth. 



Holotype: AHF No. 5414, male, 4.5 mm. Unique. 



Type locality: Station 2789, slope of Santa Monica Basin, 3Z°- 

 49'-59"N, 118°-34'-05"W, 167 m, May 22, 1954. 



Tryphosa index, new species 



(Fig. 25) 

 Diagnosis: Lateral cephalic lobes large, strongly projecting, sub- 

 acute apically, eyes pale straw-colored in alcohol, large, composed of 

 numerous hexagonal cells ; epistome large, broadly rounded in front ; 



