COPEPODA FROM CHKrlSTMAS ISLAND. 185 



abdomen (including Th. 5) "28 mm., proportional lengths of 

 abdominal segments and fiirca 12:26:12:10:9:8. Rostrum 

 (fig. 4) pointed, not visible in dorsal view, similar to that of 

 0. similis but more hooked at the tip. Form of body slender. 



1st antenna just reaches to the genital openings ; proportional 

 lengths of joints : 



.1 2 3_ J 5 6 7 8 9 . 



(16 + 16) (3+10+13+12) (14+14) (14+15 + 15 + 16) 12 28 10 12 14' 



the first four joints being subdivided by imperfect jointing in the 

 proportions indicated ; there is a sma,ll spine on the end of the 

 2nd joint. 



2nd antenna very small. 



Mandible (fig. 5) : endopodite small with two setse, exopodite 

 with five setfe. 



1st maxilla (fig. 6) small, endopodite without setse, 



2nd maxilla and maxillipede comparatively short and weak 

 but of usual form. 



1st foot (fig. 8) : exopodite three-jointed with 1.0.2 outer 

 edge spines and 0.0.4 inner edge setae ; endopodite two-jointed 

 with 1 . 5 inner edge setae and 1 outer edge seta. 



2nd foot (fig. 9) : exopodite with 1.1.2 outer edge spines and 

 0.1.5 inner edge setae ; endopodite with 1.2.4 inner edge and 

 0.0.1 outer edge setae ; an inner edge seta was found on the 1st 

 basal of the 1st and 2nd feet, but not of the 3rd and 4th, an outer 

 edge seta was present on the 2nd basals of all the swimming feet; 



3rd foot (fig. 10) : exopodite with 1.0.1 outer edge spines and 

 0.1.5 inner edge setae ; endopodite with 1.2.4 inner edge and 

 0.0.1 outer edge setae. 



4th foot (fig. 11): exopodite without outer edge spines and 

 with 0.1.5 inner edge setjB ; endopodite with 1.2.3 inner edge! 

 and 0.0.1 outer edge setae. 



5th foot of usual form. ' 



This species resembles 0. similis so closely that it is almost 

 impossible to distinguish it withovit examination of the spines ori 

 the swimming-feet. It differs from that species in the absence 

 of a spine on the 2nd joint of the exopodite of the 1st foot and 

 in the presence of a spine on the corresponding joint of the 

 2nd foot. It also differs in not having an outer edge spine on 

 the 3rd joint of the exopodite of the 4th foot, unless that spine 

 may have been accidentally knocked off in all the specimens 

 examined, as sometimes happens in the case of 0. similis, and in 

 having a well-developed spine on the centre of the outer margin 

 of the 3rd joint of the exopodite of the 2nd foot, which in 

 0. similis is only represented by a small tooth. ' 



About thirty-five specimens were found in one gathering. 



OlTHONA FALLAX, sp. n. (PI. XXTlI. figs. 9-12 ; PI. XXVIII. 

 figs. 1-3.) 



Female (PL XXVIII. fig. 3).— Length •88-- 94 mm.; cephalo^ 

 Proc. Zool. Soc— 1913, No. XIII. 13 



