Prof. T. Rupert Jones — Canadian Ostracoda. 27 



the idea, for C. ovata (Eoemer), C. elliptica, Brady, and particularly 

 C. lata, Brady, are more convex than the generality of the species ; 

 and so also Bosqueiia robiista, Brady, Eobertson, and Norman, a near 

 ally, though smaller, is relatively quite as convex. None of these 

 exhibit so peculiar a muscle-spot as is seen in Fig. 8a. The valve 

 under notice probably belonged to a Cytherella, but is different from 

 any known. 



One specimen from the Saint-Mary-River Beds on the North 

 Branch of the Milk Eiver, North-west Territory. 



The species Nos. 6 and 8 indicate marine, and No. 7 freshwater 

 conditions, for the Saint-Mary-River Beds from which they came. 

 Sometimes fluviatile species are brought down to the sea-beaches j 

 and for an example see Monogr. Tert. Entom. Pal. Soc. 1856, 

 page 17. Nos. 3, 4, and 5 (pages 23, 24) from a loose block of Saint- 

 Mary-River Beds are freshwater and brackish, without anything 

 definitely marine. No. 9 also, from the Old-Man River, is in favour 

 of freshwater conditions. 



IV. One small specimen of brownish limestone of the Saint-Mary- 

 River Beds from the Old-Man River, Alberta District, North-west 

 Territory. It contains a distinct joint-edge, in the united dorsal 

 margins of two valves of an Ostracod. 



The Old-Man River, a tributary of the Belly River, runs eastward 

 (about 48° 40' N. lat.) from the Livingstone Range (about 114° 40' 

 W. long.) ; and its "north bend" (about 49° 70' N. lat. and 113° 50' 

 W. long.) runs on the Saint-Mary-River subdivision (lowest) of the 

 Laramie formation. See the " Report of Progress " for 1882-84, 

 page 67 C, and Map No. 1. 



Candona, Baird, 1845. 



9. Candona (?), sp. indeterminate. PI. II. Fig. 9. 



Length 1-44, height?, thickness -56 ? mm. 



Dorsal junction of two valves ; hinge-line defined by the slight 

 prominences terminating the inflection of the edges. 



This resembles to some extent the external appearance of the 

 hingement and dorsal aspect of several species among the marine 

 CytheridcB, — namely, Cytherura, Xestoleberis, Krithe, — but more closely • 

 that frequently seen in the freshwater Cypris and Candona, such 

 as Cypris virens, Candona elongata, and C. Candida ; and it is here 

 placed provisionally under Candona. Of course its specific relation- 

 ship cannot be determined, for want of further evidence. 



Note. — The generic relationships of all the foregoing species are 

 for the most part uncertain, the hingement being very rarely 

 indicated by exposure or definite outline. 



EXPLANATION OF PLATE II. 

 (The figures are magnified 25 diameters.) 

 Fig. L Candona Candida (Miiller) ; a, right \ 



1. o r^,?H'' %^^^V'^^' ''"'''^''T/Al.'&omngRiye^ Pleistocene. 

 biG. 2. Cytheridea Tyrrelm, sp. nov. ; a, leit i *= 



valve ; b, edge view ; c, end view. / 



