506 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 117 



produced; third pleonal epimeron produced into a small tooth at the 

 lower posterior corner. 



Holotype: USNM 106884, ?male, 1.5 mm. 



Type locality: Abbott station 123-D-2, Ifaluk Atoll, Oct. 18, 1953. 



Material : 2 specimens from the type locality. 



Distribution : Ifaluk Atoll, Caroline Islands. 



Genus Maera Leach 



This is perhaps the most abundant genus in the collections. Its 

 taxonomy is in a confused state and seriously in need of a revision by a 

 single specialist. The materials at hand are especially difficult to 

 identify because of the lack of large suites of material from a single 

 locality and because most of the specimens are immature. There is 

 little difficulty in identifying M. insignis and M. othonopsis and the 

 problem lies in those species having second gnathopods with transverse 

 palms. Few of these specimens are mature and apparently the 

 metamorphosis of the palmar configuration into the adult sculpturing 

 passes through several stages in both males and females and all the 

 initial stages are similar. Although the adult palms in M. inaequipes, 

 M. pacifica, and M. quadrimana differ, they are alike in the juvenile 

 stages. 



In order to identify these species, one must examine the telson. 

 Each lobe of the telson in M. inaequipes is deeply notched (Schellen- 

 berg 1938a, fig. 18) but to observe this character it is necessary to 

 dissect and mount the telson of each individual, a laborious procedure 

 in such small animals. Maera pacifica and M. quadrimana have 

 blunt telsonic lobes (Schellenberg 1938a, figs. 19, 22) and often can 

 be separated from each other by the stoutness of the second articles 

 on pereopods 3-5 of M. imcifica (see Schellenberg 1938a, figs. 19-22), 

 Unfortunately, many of the specimens at hand have lost the pereopods 

 so that positive identification is impossible. When one specimen in 

 a lot can be identified as one or the other species, I have included the 

 remaining damaged specimens in the identification. 



All specimens of Maera quadrimana in the Reish collections have 

 stout basal articles on the last 3 pairs of pereopods, formmg a per- 

 plexing exception to Schellenberg's otherwise neat separation of 

 M. pacifica and M. quadrimana. I have no doubt that these specimens 

 are M. quadrimana as seen in the figures of the gnathopods presented 

 here. As there are no clear differences in the young of M. pacifica, 

 one must rely on the length of the defining palmar tooth of gnathopod 2 

 in the young of both sexes, which is long in M. pacifica and short in 

 M. quadrimana. 



