84 



COPEPODA 



posterior end of the genital somite, have the 24 and 25 segments fairly well separated; the segments 

 2 and S<s>g are of equal length, and a little longer than the segment 20; the segment 18 is distinctly 

 i-i as long as 21, and the segment 24 is a little longer than 23. The posterior seta of the segment 

 23 scarcely extends to the tip of the segment 24. The antennae have the exopodite almost twice as 

 long as the endopodite, and the third basipodite of the mandibiilac has the Si i shorter than figured 

 by Giesbrecht (Taf. 14 fig. 17). The inaxillulae^ maxillae and the maxillipeds are scarcely different 

 from those described by Giesbrecht; a small pointed process, placed behind the articular cavity of 

 the maxillipeds, is better developed than in preceding species (text-fig. 20 a). The first pair of legs is 

 like Sars' fig., but the Se Re I extends a little beyond the end of the Re II. In the second pair of 

 legs (text-fig. 20 e) no trace of articulation was found between Ri I — II, neither anteriorly nor posteriorly; 

 the articular membrane between Re I — II is anteriorly indicated by a faint line. Glandular pores 

 are found at the base of the respective Se of Re I— III in the last three 'pair of legs; the articular 

 membranes between the Re I — II in pes III — IV are scarcely better developed than in the second 

 pair of legs, but the articulation between Ri I— II is marked not only by a lateral incision as drawn 

 by Sars, but also by a faint line anteriorly (text-fig. 20 f). 



The structure of the labnivi is in most respects like that of Ch. artiiattcs; the most interest- 

 ing differences are found at the oral surface viz: the wanting transverse row of spinules behind 

 the median circular spot Nr. 3, and the lateral group of spinules anteriorly which is divided into a smaller 

 anterior and a bigger posterior portion. The lamina labialis (fig. 2 a) consists posteriorly of a chitinous appa- 

 ratus which is subdivided into a median and two lateral clumsy teeth, the posterior margin of which is 

 somewhat striated; the lamina is gradually sloping anteriorly, and overlapped by the slightly concave 

 posterior margin of an almost semicircular chitinous plate. In front of the lamina labialis we observe 

 on the posterior wall of the pharyngeal cavity in the middle a smooth longitudinal area, and on each 

 side of this a minutely granular area, as seen in fig. 2 a. Laterally a series of fairly slender setae, 

 which are situated on a chitinous lists, apparently a continuation of that supporting the serrula 

 6-dentata, is found. Behind and medially, a longitudinal series of about 20 more slender setae; this 

 series reaches only a little beyond the anterior limitation of the lamina labialis. The number of the 

 serrulae behind the lamina is three, arranged as seen in fig. 2 a. 



The number of series of hairs behind the labial lobes etc. is in the main like that of Gaidius 

 (of. fig. 7 f). The series lateral i se6ras to be wanting, series lat. 2 consists of about 30 short 

 delicate hairs which are anteriorly placed in a single longitudinal row, and posteriorly in an irregular 

 group; the series lat. 3 has posteriorly an oblique row of short hairs, on the medial side of which 

 we find an area consisting of about 20 short bristles, and anteriorly one or two short rows, one of 

 which is continued as a long row to the end of the labial lobe. The series lat. 4 is medially placed 

 transversely with backwards directed convexity, as seen in fig. 2 a; laterally to this, and probably be- 

 longing to it, a triangular group of densely placed hairs is found. The series lat. 5 is represented by 

 a group of densely placed short hairs, which are placed in a triangular area, pointed in front. The 

 connection between the two last series and the hairs on the lateral lobes was not made out. 



Y (Stage V). Size: Female from St. 154 measured 3-08 mm.; anterior division 2-3 mm.; uro- 

 some 078 mm. 



