96 U.S. NATIONAL IMUSEUM BULLETIN 260 



and article 6 is very slender. The condition of dactyls is mixed in 

 Monoculodes^ for in some species they are long and saber shaped \^M. 

 longirostris (Goes) ] whereas they are very short and clawlike in other 

 species [M. carinatus (Bate)]. Most members of Oediceroides have 

 the large, saber-shaped dactyls. This character alone appears to have 

 no strong generic value. Aceroides sedovi is similar to A. phyllonyx 

 in the aspect of pereopods but article 5 is more weakly lobate. 



Aceroides kobjakovae Bulycheva (1952) has the ventrally excavate 

 coxae and lateral row of setae on article 4 of pereopods 1 and 2 but 

 article 5 is neither shortened nor lobate ; the mandibular cutting edge 

 projects strongly and is as well toothed as it is in Monoculodes and 

 Oediceroides but it is unlike the type-species of Arrhls. Furthermore, 

 the mandibular palp of A. kohjakovae is powerful. Article 2 of an- 

 tenna 1 is as long as article 1, in contrast to A. latipes Sars. Aceroides 

 Ihnicola has a small rostrum, excavate coxae and similar articles 4-6 

 of pereopods 1 and 2 but differs from A. kohjakovae by the distally 

 expanded coxa 1, the long article 2 of antenna 1, the unguiform, un- 

 expanded pereopodal dactyls, which are shorter than article 6, and the 

 rather strongly setose inner plate of maxilla 1 (with 6 setae) . K. H. 

 Barnard (1925) remarked that the inner lobes of the lower lip of A. 

 IhnicoJa are completely coalesced ; except for this character, which is 

 unknown in O. {Patoides) synparis, the two species would be con- 

 generic and more closely similar to each other than they are to 

 Aceroides latipes. Aceroides limicola and 0. synparis correspond in 

 antennae, mandibles, gnathopods, and pereopods and differ from each 

 other only by the unexpanded coxa 1 and the distally rounded (not 

 slightly emarginate) telson of O, synparis. Aceroides kohjakovae is 

 removed from this pattern only by the unmodified article 5 of pereo- 

 pods 1 and 2 and the more strongly saber-shaped dactyls. This com- 

 bination is thus a bridge to A. latipes and A. sedovi Gurjanova, but 

 both of those species have a less strongly produced mandibular cutting 

 edge, while A. sedovi has a more powerful mandibular palp than does 

 A. latipes. Thus, A. latipes^ the type-species, is the most specialized 

 member of the group. 



The Aceroides complex differs from all species of Oediceroides (if 

 tho two species mentioned above are removed) by the very short or 

 obsolete rostra. A species to be described in sequel has lost all ves- 

 tiges of the rostrum as in A. plifyUonfyx. 



Because the gnathopods of Aceroides are more like those of Monocu- 

 lodes than of Oediceroides., the condition of the short or obsolete rostra 

 of Aceroides is highly pertinent as a generic character. The great 

 variability in pereopods 1 and 2 of the Aceroides complex, relative to 



