FRESHWATER OSTRACODA FROM CANADA AND ALASKA 



By Prof. G. 0. Sars, 

 University, Oslo, Norway. 



INTRODUCTORY 



The freshwater Ostracoda of North America are still rather imperfectly 

 laiown, the only fairly complete account being that given by C. H. Turner in 

 the Synopsis of the Entomostraca of Minnesota, published in 1895. From Canada 

 very few species have as yet been recorded, and it will therefore be of interest 

 to have further knowledge of that part of the Fauna in the more northern regions 

 of America. 



The present account is based upon collections made mainly by Mr. Frits 

 Johansen, and taken chiefly in the neighbourhood of Ottawa.^ The collections 

 comprise sixteen species in all, five of which appear to be new to science, and 

 a 6th {Cypns barbata, Forbes) constituting the t^ype of a new genus. This and 

 the five new species are figured on the five plates accompanying the present 

 account, and detailed descriptions of them are given in the text. 



Family CYPRIDAE 



Sub family CYPRINAE 



Group NOTODROMIDES 



Genus Cyprois Zencker 



Remarks. — Of this well-defined genus, in the restriction now generally 

 accepted, only a single species is as yet known, viz., C.'marginata (Strauss). 

 I am now enabled to add another nearly allied, but evidently distinct species 

 from Canada. 



1. Cyprois occidentalis, n. sp. 



Plate I. 



Specific Characters. — Female. Shell somewhat compressed, seen later- 

 ally (fig. 1), short oval or subquadrangular in shape, greatest height a little 

 behind the middle and about equal to | of the length, dorsal margia gently 

 arched in the middle; ventral margin very slightly sinuated, both extremities 

 obtusely rounded off, the anterior a little broader than the posterior; seen 

 dorsally (fig. 2), narrow ovate in outline, with the greatest width behind the 

 middle and scarcely exceeding f of the length, anterior extremity gradually 

 narrowed to a sharp point, posterior more obtuse. Valves very thin and trans- 

 parent, without any obvious sculpturing, and provided at each extremity with 

 a well marked hyaline rim crossed by fine curved striae, that of the anterior 

 extremity being in particular very broad and conspicuous; hairy coating very 

 scarce. Structure of the several appendages (see figs. 4-7, 10-12) on the whole 

 very similar to that in the type species. ' 



Male (fig. 3) of smaller size than female, and slightly differing in the shape 

 of the shell, which is more compressed and, viewed laterally, higher in propor- 

 tion to the length, with the dorsal margin more arched; posterior extremity, as 



1 As only three of the sixteen species listed in this report wsra repressntel in th3 Arctic collections, an apolo<'y ssem s 

 needed for the inclusion of the large mass of extra-limital material which is ojtaida of the propsr purview of t^e Arctic 

 expedition publications. The local Ottawa spesiTnens W3ra S3nt to Professor Sirs withojt proper explanations by the 

 collector, in his zeal for early publication, iudependently of the Arctic Publicatioas CoiimitteB, and aa" a comprehensive 

 report was prepared by Professor Sars including both the Arctic and the saathsrn specimens, it was thought best not to 

 break up the report. 



17332—1} 



