﻿COPEPODA 5g 



also been examined at several other stations (f. inst. (innolfsvig Iceland), where I often fonnd that the 

 small specimens had the nrosome comparatively loni,^er (f. inst. ant. div. 1-9 x nros.), bnt with several 

 exceptions. According to vSars the anterior division of J's. grdc/lis is comi)aratively more slender; I 

 fonnd, certainl}-, that a specimen of t\pns iiiajoi- had the anterior division 2-3 as long as wide, one of 

 typns gracilis 27 as long as wide, and one of t\-pus tloiigatus 2-4 as long as wide, bnt as several 

 exceptions were fonnd, I was not able to use this character. I first got the impression that the 

 characters fonnd in the comparati\-el\- long antennnlae and natatory legs in se\-eral specimens of 

 the t\pus gracilis were usefnl, bnt a stud}- of greater material made it evident to me that they 

 were too variable to be of an\' value. The feature which marks out some specimens as gracilis 

 is the curiousl}- prominent forehead, which is in an\' case very seldom fonnd in the l)iggest as 

 well as in the smaller specimens. But as all transitions were found between the different shape of 

 head, even in specimens which in other respects were most like gracilis, it was impossible for me to 

 accept more than a single species. 



Description, fif. I was not able with certainty to find any secretory pores in the natatory legs. 



The liihniiii proper, which is the most posterior of a row of more or less prominent elevations 

 found behind the insertion of the rostral filaments (text-fig. 13 a), has along its hinder margin, on each 

 side, a group of fairh' long hairs, and in the middle, somewhat in front, a hair\- protuberance. The oral 

 surface of the labrum possesses four groups of short hairs, as seen in fig. 8 (PI. I). The lamina la- 

 bialis has along its posterior margin three indistinct rounded eminences; oralh' the two usual longitudinal 

 series of fairly short hairs are obser\'ed, of wliich the more lateral is longer and with longer hairs. 

 Behind the lamina a transverse row of short hairs or teeth is obser\'ed and a similar but longitudinal 

 one is fomid inside the serrula 6-dentata. Between the labial lobes, which are covered with hairs, the 

 arrangement of which were not made out, about four gronjis of hairs are found, of which the hind- 

 most, which has longer hairs, stands more laterally. Betw^een this and the lateral margin l:iehind the 

 labial lobes 2 oblique groups of hairs are present. 



Behind the area lahialis proper is fonnd on each side a large group of fairh' long hairs in addition 

 to a few hairs more laterally, and in the middle a triangular group, placed more posteriorly and with 

 its hindmost, wider part fused with a rather irregular group of setae placed between the insertion of 

 the maxillae. 



fc?. As far as the full-grown male.s, of which comi^aratively few were examined, were concerned, 

 I could not find other differences between the different specimens than that of size, varying from i-i 

 to 1-4 mm. Canu and Sars have given descriptions and figures of the rudimentary mouth limbs. In most 

 specimens an indication between the head and first thoracic .somites was .seen as figured by Cann as 

 well for the male as for the immature specimens. 



Y. (Stage IV). Size: r2— 1-9 nun. The last thoracic somite is generally more produced than 

 that of the mature females, and dor.sally a more or less marked limitation between the two last 

 .somites is found Uext-fig.s. 12b — c). The uro.some is comparatively short and sometimes only one third 

 of the anterior division; according to Kraefft (fig.s. 15 -iS) the two first somites are better separated 

 in the males than in the females; gencrallv no such differences were ob.served, but in .^^ome young 

 female.s, especiallv of the smaller "variety", the two first somites were somewhat produced below, 



