NO. 6.] ACCOUNT OF THE SPECIES. 59 



agree perfectly with the 2 species recorded by Dr. Giesbrecht, and accordingly 

 ought to be referred to the same genus. 



8. Undeuchceta spectabilis, n. sp. 

 (PI. XV, XVI). 



Specific Characters. Body of female rather robust, with the anterior 

 division oblong oval in form, that of male considerably more slender, cephalic 

 segment coalesced with the 1st pedigerous one; last segment, however, well 

 defined in both sexes, though very small, its lateral corners produced in 

 female to a short, deflexed, angular projection. Front produced below to a 

 very small, pointed, rostral prominence. Tail in female scarcely more than Vs 

 as long as the anterior division, and having the segments very sharply marked 

 off from each other. Caudal rami very short, scarcely as long as they are 

 broad, and somewhat divergent, apical seta? very strong and densely plumose. 

 Anterior antennae in female about the length of the anterior division of the 

 body, and 24-articulate, 1st joint with 2 very conspicuous plumose setae ; those 

 in male comparatively more slender, and composed of only 22 articulations, 

 partly clothed with delicate sensory filaments. Posterior maxillipeds very 

 slender, 2nd basal joint exceedingly long and narrow, terminal part short, 

 not even attaining a length equal to Vs of that joint. 1st pair of natatory legs 

 with the first 2 joints of the outer ramus coalesced; 4th pair with 5 strong 

 spines inside the 1st basal joint. Last pair of legs wholly wanting in female, 

 in male exceedingly large and powerful, with both legs biramous and of rather 

 complex structure. Length of adult female 8 mm., of male 6 mm. 



Remarks. This, next to Euchceta norvegica, is the largest Calanoid col- 

 lected during the Expedition, equalling in size even the largest specimens of 

 Calanus hyperboreus. This, indeed, will suffice to distinguish it from the 2 

 other species of the genus, which are very much smaller. 



Description of the Female. 



The length of the specimen examined, which seems to be fully grown, 

 measures no less than 8 mm., not including the caudal setae; and this form 

 accordingly attains a size nearly twice that of the largest of the 2 species 

 recorded by Dr. Giesbrecht, U. major, the length of which is only 4'50 mm. 



