6 Canadian Arctic Expedition, 1913-18 



Seta of the dorsal edge very small and attached near the apex. Copulative 

 appendages (fig. 14) oblong oval in shape and divided behind into two obtusely 

 rounded lappets. Ejaculatory tubes (fig. 15) very large and each enclosed 

 within a roomy, muscular sheath; both extremities funnel-shaped. 



Colour, according to Forbes, a dirty yellowish-brown, with a reddish-brown 

 patch on either side. 



Length of the specimen examined 3 • 40 mm. 



Remarks. — This large and handsome ostracod has hitherto onty been 

 observed by Prof. S. A. Forbes, who in the above-quoted paper has given a 

 rather full description of the female accompanied by some figures. The descrip- 

 tion, which has been reproduced in extenso in Mr. Turner's monograph, agrees 

 on the whole pretty well with that here given; though, because the specimen 

 examined by me was of a different sex, some differences in the shape of the 

 shell, as seen laterally, are found, in addition to the sexual transformation of the 

 maxillipeds. Forbes gives the length of the shell to 4 mm. and supposes it to 

 be the largest freshwater ostracod known. It is, however, in this respect con- 

 siderably surpassed by some of the South African forms recorded by the present 

 author, particularly by the big species of the genus Megalocypris. 



OccTJEEENCE. — The above described solitary specimen was taken by Mr. 

 A. G. Huntsman on June 11, 1920, in sloughs, three miles northeast of Medicine 

 Hat, Alberta. Forbes obtained the species from the Yellowstone river, Yellow- 

 stone Park, Wyoming (1893, Prehm. Rep. Aquat. Invert. Fauna). 



Genus Cypricercus G. 0. Sars 



5. Cypricercus affinis (Fischer) 



Occurrence. — Several specimens of this form have been collected by F. 

 Johansen. They were taken at the two following localities. 

 Pools at Billings bridge, Ottawa, Ont., May, 1923. 

 Bracldsh pond at Teller, Port Clarence, Alaska, Aug. 3, 1913, C.A.E.* 



6. Cypricercus horridus, n. sp. 



Plate III, figs. 1-7. 



Specific Characters. — Female. Shell very tumid, seen laterally (fig. 1), 

 rather regularly oval or elliptical in shape, greatest height nearly in the middle 

 and somewhat exceeding half the length, dorsal margin gently arched, with the 

 greatest curvature in the ocular region, and joining the hind-edge without any 

 angular bend, ventral margin slightly sinuated in the middle and somewhat 

 bowed in front, both extremities evenly rounded off, the anterior one consider- 

 ably broader than the posterior — seen dorsally (fig. 2), broadly oval in outhne, 

 with the greatest width attaining about f of the length, both extremities some- 

 what blunted, the posterior more so than the anterior. Valves, as in the other 

 species of this genus pronouncedly unequal, the left one considerably overlapping 

 the right in front, as also somewhat behind; surface very uneven, being every- 

 where thickly covered with short and stout, somewhat squamiform spikes 

 curving as a rule, backwards, and giving the shell a very scabrous appearance; 

 a rather dense coating of fine hairs may also be observed. Structure of the 

 several limbs (see figs. 3-6) on the whole agreeing closely with that in the other 

 known species. Caudal rami (fig. 7) exhibiting the appearance characteristic of 

 the genus, being much produced, narrow linear in shape and perfectly straight, 

 distal apical claw not attaining half the length of the ramus. 



Colour not yet ascertained. 



Length of adult female 1-05 mm. 



Male unknown. 



•See pp. 3-4 in Part N, of this volume. 



