Introduction 



On studying the physical and biological conditions of the Oyster- 

 beds of western Norway, Dr. H. Gean has detected in some of 

 them a very remarkable Calanoid, which he has kindly placed in 

 my hands for description. This Calanoid is indeed of very par- 

 ticular interest, belonging, as it does, to a hitherto only imperfectly 

 known genus, the type of which is derived from the tropical part 

 of the Atlantic Ocean (the Gulf of Guinea). The occurrence of a 

 species of this genus so far north is very perplexing, and is apparently 

 to be accounted for by the peculiar physical conditions prevailing in 

 the said basins, as spoken of at the close of this paper. 



I give below diagnoses of the genus and the species, and 

 also a detailed description of the latter, which I have muen pleasure 

 in naming in honour of its detector, the distinguished Norwegian 

 naturalist, Dr. H. Gran. The accompanying plates have been pre- 

 pared with the utmost care by the autographic proceeding employed 

 by the present author in most of his recent papers. 



Gen. Paracartia, Scott, 1894. 



Generic Characters. — General appearance somewhat resembling 

 that of Acartia; the sexual differences, however, much more strongly 

 marked. Last segment of metasome in female very large, and pro- 

 duced on each side to a broad wing-like expansion; that of male 

 simple, with the lateral parts not expanded. Urosome in female 

 comparatively short, 3-articulate, with the genital segment very large 



