136 



plates; the 2 posterior trunk-segments, however, very small and not produced 

 at all laterally. Tail normally developed, and composed in female of 4, in male 

 of 5 segments. Caudal rami comparatively small. Anterior antennae resembling 

 in structure those in Artotrogus, though somewhat coarser; those in male (according 

 to Scott) distinctly hinged, but without supplementary sesthetasks. Posterior 

 antennae very powerfully developed and strongly clawed at the end, outer .ramus 

 present as a delicate setiferous lamella. Siphon obsolete, the 2 lips being scarcely 

 at all produced. Mandibles terminating in a simple point. Maxillae with 2 very 

 unequal lobes. Maxillipeds comparatively slender, and of quite normal structure. 

 Only 3 pairs of natatory legs present, 1st pair with both rami only composed 

 of 2 joints. 4th pair of legs wanting, or only present as a very slight rudiment. 

 Last pair of legs represented by a small bisetose joint accompanied outside by 

 the usual bristle. 



Remarks. This genus was established in the year 1893 by Scott, to 

 include a peculiar Copepod, P. Richardi, found by him on the Scottish coast; 

 and subsequently also observed by Giesbrecht. The generic name proposed by 

 Scott is somewhat inappropriate, as the affinity of this genus to Artotrogus is a 

 very remote one. The genus comprises as yet 2 nearly- allied species, one of 

 which will be described below. 



75. Parartotrogus arcticus, Scott. 



(PL LXXTX). 



Parartotrogus Richardi, var. arctica, Scott, On some Entomostraca collected in the Arctic Seas; 

 Aim. Mag. Nat, Hist., Ser. 7, Vol. VIII, p. 352, PI. VI. 



Specific Characters. Female. Body comparatively more slender than in 

 the type species, with the anterior division less dilated, and oval in outline. 

 Cephalic segment very large, occupying about half the total length, but not nearly 

 so much expanded in the middle as in P. Richardi, the lateral edges being 

 evenly arcuate; frontal part conspicuously exserted and broadly truncated at the 

 end. Epimeral plates of the 2 succeeding segments well defined and rounded at 

 the end. The last 2 trunk-segments abruptly much narrower and subequal in 

 size. Tail about equalling in length half the anterior division; genital segment 

 fully as long as the 3 succeeding segments combined, and gradually widening 

 anteriorly, forming on each side in front a somewhat projecting angle; anal 

 segment longer than the preceding one. Caudal rami somewhat longer than they 

 are broad and rather far apart, apical setae comparatively short, the inner mediate 

 one scarcely exceeding half the length of the tail. Anterior antennae not quite 

 attaining half the length of the cephalic segment, and somewhat bent at the base. 



