145 



Gen. 36. Hemicyclops, Boeck, 1873. 



Syn: Hersiliodes, Canu (part). 

 Platycheiron, Scott. 



Generic Characters. Body cyclopoid in shape, with the anterior division 

 sharply marked off from the posterior, and more or less flattened. Tail com- 

 paratively slender, with the caudal rami not much produced. Anterior antennae 

 of moderate length and composed of 7 joints, none of which are expanded 

 in front. Posterior antennae with the terminal joint very short. Maxillae 

 provided with 2 setae inside the apical spines; palp produced inside at the 

 end to a well-defined small setiferous lobule. Anterior maxillipeds with several 

 ciliated setae in addition to the 2 apical spines. Posterior maxillipeds in female 

 moderately strong, but scarcely prehensile, being clothed with rather long, 

 partly spiniform setae; those in male powerfully developed, with the propodos 

 very broad and flattened and coarsely denticulated inside. Natatory legs all 

 of normal structure, with both rami 3-articulate. Last pair of legs biarticulate; 

 distal joint broad, lamellar, and edged with 3 spines and a delicate apical bristle. 



Remarks. This genus was established as early as the year 1873 by 

 Boeck, to include a peculiar Copepod found by the present author in the upper 

 part of the Christiania Fjord. Its true relationship to the other Cyclopoida 

 was however not recognised by Boeck, who placed the genus near Cyclops 

 within the group of gnathostomous Copepoda. The genus Hersiliodes of Canu 

 agrees in most characters with that here under question; but of the 3 species 

 recorded by him only the two, viz., H. Thompsoni and H. puffini can with 

 full certainty be adduced to Boeck's genus; the 3rd species H. Pelseneeri 1 ) 

 seems to me to be so different from the other 2, both as to the general form 

 of the body an to the structure of some of the appendages, that it hardly can 

 be combined with them in the same genus. If the generic name Hersiliodes 

 is to be retained, it must of course be restricted to that species. Of the 

 various species described by T. Scott, and provisionally referred to the genus 

 Lichomolgus Thorell, there are two which unquestionably belong to the present 

 genus, viz., L. littoralis and L, aberdonensis, the first of them being appa- 

 rently identical with the Norwegian species here described. Scott himself was 

 well aware of the considerable differences which these two species exhibit, as 

 compared with the typical Lichomolgi, and in a supplementary note 2 ) suggested 



') According to Giesbrecht, this species is identical with the form described at an 

 earlier date by Grube as Antaria latericia. 



2 ) Annals of Scottish Nat. Hist. 1892, p. 153. 



