11)1 



proximal joint scarcely at all expanded inside, distal joint somewhat longer, with 

 one of the marginal seta3 attached to the outer edge in front of the middle. 



Colour pale whitish, with a slight yellowish grey tinge. 



Length of adult female about half a millimetre. 



Remark*. This form may be easily recognised by the conically produced 

 frontal part, the peculiar form of the genital segment, and the total absence of 

 any visual organ. 



Occurrence. I have only met with this peculiar Copepod in the upper 

 part of the Christiania Fjord, where some few female specimens were found in a 

 depth of about 30 fathoms, muddy bottom. 



64. Idyella exigua, G-. O. Sars, n. sp. 



(PI. LVIIT. fio. 2). 



Specific Characters. Female. Anterior division of body somewhat less 

 expanded than in the preceding species, with the cephalic segment of inferior 

 size, not attaining twice the length of the 3 succeeding segments combined, and 

 more evenly contracted anteriorly, front narrowly rounded. Urosome somewhat 

 exceeding half the length of the anterior division, genital segment exhibiting on 

 each side 2 successive triangular lobes separated by a deep median incision ; 2nd 

 segment with the posterior corners conically produced. Caudal rami about as in 

 I. paUiilnla. but with the seta of the outer edge obsolete. Eye very conspicuous 

 even in preserved specimens, exhibiting 4 dark-coloured lenticular bodies arranged 

 in pairs in the usual place. Anterior antennae comparatively more robust than 

 in the preceding species, with the terminal part shorter, not attaining the length 

 of the 2 preceding joints combined. Posterior maxillipeds with the 2nd joint 

 conspicuously dilated beyond the middle. First pair of legs resembling in struc- 

 ture those in 1. pallidula, but with the proximal joint of the inner ramus less 

 broad and fully twice as long as the distal one. Last pair of legs less slender, 

 proximal joint produced at the end inside to a narrow conical projection carrying 

 2 slender setse; distal joint densely hairy, with one of the setse issuing from the 

 lower face in front of the middle. Ovisac rounded, only containing a limited 

 number of comparatively large ova. 



Colour not yet determined. 



Length of adult female 0.44 mm. 



Remarks. This form is unquestionably congeneric with the preceding 

 one, as it exhibits the same characteristic structure of the posterior maxillipeds and 



