FROM CHRISTMAS ISLAND. 291 



is not so wide as in 0. obiiosas, being at its widest pai't, a little 

 Ijehind the anterior margin, only just ^ as wide as the widest part 

 of the cephalon (PI. XII. fig. 1). The points of the segment are 

 slightly conti'acted, the distance between them being only | of the 

 width of the cephalon. The total length is '9 mm. 



The most noticeable features, in comparison with C. obkosics, 

 are the sharp slender points to both the 3rd and 4th thoracic 

 segments (PI. XII. fig. 2), and the somewhat larger eyes, separated 

 by I'ather less than theii- own dianietei-. The foi-m of the 

 abdomen and furca is v'eiy similar in both species. 



CoRYc^us OBTUsus Dana. (PI. XII. figs. 4-6.) 



Cor>/cc8i(,s obtasas Dana. 

 C. obtusus Giesbrecht. 

 0. ooalis Dahl. 



According to Dahl (5), Giesbrecht is in error in his identification 

 of the species which he has described and figured under the 

 name of G. obtasus Dana, Dana's species being different and not 

 found sxibsequently. He believes that Giesbrecht's description 

 really refers to the species which Glaus (2) had described under 

 the name of C. ovalis. 



Under these circumstances the course least liable to cause 

 confusion would be to reject both Dana's and Glaus's names ; 

 however, for the present, I assume that Giesbrecht's name is 

 correct. Eighteen specimens, females, of the species in question 

 occurred in the collection, in three gatheiings. 



The distinguishing characters are the size, 1'05-1"1 mm., the 

 wide spreading third thoracic segments, the bhmt tips to the 

 fourth thoracic segments (PI, XII. fig. 5), the fine seta^ in front 

 of the genital openings, the anal segment as long as it is bi'oad 

 at the base and nearly as long as the furca, and the single 

 seta on the endopodite of the fourth foot (PI. XII. fig. 4). 



Distribution. Red Sea, Arabian tSea, Indian Ocean, Tropical 

 Pacific, Tropical Atlantic. 



CoRYC^us TENUIS Giesbrecht. (PI. XII. figs. 8, 9.) 



Of the forms with tv/o seta) on the endopodite of the foui'th 

 foot and a moderately long furca there are two species, females, 

 in the collection. One of these is described below as ne^v, the 

 other appears to be ('. tenuis. In Dahl's (5) key the choice lies 

 between C. anglic>(,s and C. tenuis, the former being distinguished 

 in the key by the presence of a corner on the inner side of the 

 lateral prolongation of the 3rd thoracic segment and by a small 

 hook-like ventral pi-ocess on the j^roximal end of the abdomen. 

 Both these characters are present in my specimens and, if the 

 table were closely followed, they ought to be C. anglicihs. They 

 ai-e, however, not that species, being distinguished fi-om it Ijy the 

 shorter genital segment with much more slendei- seta?, the form of 

 the anal segment, which is parallel-sided and about twice as long 



