GAMMARIDEAN AMPHIPODA 93 



Gills occur on pereonites 2-7; they are large, un plaited and liave 

 one accessory appendage each, except that of pereonite 6, which has 

 two; gills of gnathopod 2 and pereopod 1 are the largest and are 

 basally folded more complexly than succeeding gills; the next 3 gills 

 are of medium size (see figure of gill of pereopod 4) and the gill of 

 pereopod 5 is smallest, scarcely larger than its coxa. Accessory ap- 

 pendages are tubular, but on some gills they are basally tumid or 

 have rounded basal lobes. 



Only one female occurs in the samples ; it lacks any secondary sexual 

 differences from the male. The brood lamellae are rudimentary. 



DisTREBTJTioN. — Soutliem California, 183-513 m. 



Oedicerotidae 



Relationships of the Genera Acer aides, Anoediceros, Arrhis, Lopiceros, 

 Monoculodes, Oediceroides, and Patoides 



A number of intergrading species discovered in the last four decades 

 have obscured the strong distinctions formerly loiown for the genera 

 Oediceroides Stebbing, Aceroides Sars, Arrhis Stebbing, and Monoc- 

 ulodes Stimpson. The four type-species of those genera might be 

 visualized as standing on the four corners of a square. A number of 

 intersections and intermediate positions among the several genera 

 would occur if a series of lines connecting all four positions is drawn. 

 The corners holding the type-species of Monoculodes and Oedicerokles 

 (including Patoides) are surrounded by tight clusters of numerous 

 species that closely resemble the types. The corners holding Arrhis 

 and Aceroides have one or two species each. In various intermediate 

 positions among all four genera stand such species as (1) Monocidodes 

 latissimanus Stephensen (1931), which might also be assigned to 

 edioeroldes ; (2) '"''Oediceroides'''' {Patoides) syn/paris J. L. Barnard 

 (1964b), which bridges the gap between ed'icero'ides and Acero'ides 

 but which also has connections with Arrhis; (3) a new species of 

 '"'•Patoides''^ to be described, which is highly atypical of Patoides; 

 (4) a new species of ^'^Aceroides" which is atypical of Aceroides and 

 has several characters of Patoides; (5) Oediceroides (Lopiceros) 

 forensia^ which differs in several ways from typical species of 

 Oediceroides; and (6) the several species now assigned to Aceroides, 

 A. kohjakovae J^u\JcheYil (ld5'2),A. sedoviGurjaiiOYH (see 1951) and 

 A. limicola K. H. Barnard (1925). 



