FROM CHRISTMAS ISLAND. 283 



feet of the female, which is beak-shaped in one group and semi- 

 circulax' in the other. There can be no doubt tliat these characters 

 are, collectively, of generic importance, and I propose the name 

 Corycella for that subdivision, as typified by C. gihbulus, which 

 is marked by the possession of a beak-shaped ventral process, 

 leaving the name Corycoeus for the remaining sj)ecies, of which 

 O. speciosus may be selected as the type. 



The genus Corycams was founded by Dana in 184.5 (6), his 

 diagnosis being repeated in 1846 (7), but no species belonging to 

 the genus was described till 1849 (8). Dana's definition of the 

 genus includes both the genera defined above, and his papers 

 describing the species, first published without figures in 1849 (8), 

 and afterwards with figures in 1852 (9), contain forms belonging 

 to both Corycella and Corycceus, but do not indicate any one of 

 them as forming the type of the genus. 



The principal differences between Cwycceus and Corycella may 

 be summarized as follows : — 



Genus Corycella, nov. Genvis Coeyc^us Dana. 



Abdomen of <? and $ one-jointed ; Abdomen of (J and $ usually two- 



4th thoracic segment without lateral jointed ; 3rd and 4th thoracic segments 



points, not distinct from 3rd thoi'acic distinctly separate, the latter with 



segment. Ventral process beak-shaped lateral points. Ventral process semi- 



in ^ . 2nd antenna with setae on 1st and circular in ^ . 2nd antenna with the 



2nd basal joints distantly feathered ; setae on 1st and 2nd basal joints not 



terminal spine short in ^; inner edge of feathered; terminal spine elongated in 



2nd basal coarsely feathered. ,J> inner edge of 2nd basal usuallj' with 



one or more strong teeth. 



1st to 3rd feet, exopodite with 0.0.1 1st to 3rd feet, exopodite with 1.1.3 



outer edge seta;. outer edge setae. 



4th foot without endopodite, exopo- 4th foot with endopodite bearing one 



dite with 0.0.1 outer edge setae. or two setae, exopodite with 0.1.1 outer 



edge setae. 



The one- jointed abdomen and the feathered setse of the second 

 antennae occur, as Dahl has pointed out, as characters of im- 

 matu.rity in the genus Corycceus. 



Giesbrecht (10) recognises five species of Cory cams in the 

 group for which the name Corycella is proposed, viz., C. gihhulus 

 Giesbr., C. concinnus Dana, C. rostratths Glaus, C. carmatus 

 Giesbr., and C. longicaudis Dana.' In Dahl's revision of the 

 genus (5) he accepts C. gibbuhis, C. concinnus, C. carmatus, 

 C. rostratus, and, under the new name of C. tenuicattda, C. longi- 

 caudis, asserting that Dana's description of C. longicaudis really 

 refers to C. S2ieciosus juv., a view which is strongly supported 

 by Dana's figures. Dahl also recognises Dana's (8) description of 

 C. gracilis as being good, but does not give any reason for this 

 opinion. Dana's description and figures of G. gracilis evidently 

 refer to a male of Corycella, but the specific differences between 

 the males of this genus are so slight that it does not appear 

 possible to refer the description and figures with certainty to any 

 particular species. Dahl's belief that G. j^elhicid^is of Dana is the 

 female of what he recognises as C. gracilis also appears to be 

 a mere conjecture, there being very little evidence for or against 



