Pro/. T. Rupert Jones — Canadian Ostracoda. 23 



Cythebidea, Bosquet, 1850. 



2. Cttheridba Tykrellii, sp, nov. PI. II. Figs. 2a, h, c. 

 Length -72, height -44, thickness -32 mm. 



Trigonal, broadly rounded in front, obliquely subacute behind ; 

 surface not much raised, almost flat, and sloping off suddenly to the 

 edges. Two or three small knobs or pimples are groujDed on the 

 middle of the valve, and near by there is one larger and closer 

 to the dorsal edge. The surface also is punctate. 



The outline and sculpturing of the shell are not strange in 

 Cytheridea ; G. Muelleri, var. torosa, Jones (Monogr. Tert. Entom. 

 p. 42, pi. vi. fig. 12, is one of the nearest of the published forms). 

 The species under notice, named after its discoverer, is rather 

 common in the marl from Eolling Eiver, Manitoba. It probably 

 lived in brackish water. 



The species Nos. 1 and 2 indicate freshwater and brackish con- 

 dition for the deposits in which they occur. 



II. Seven small pieces of an " unattached " block, found on the 

 South Branch of the Milk Eiver. They consist of dark-brown or 

 blackish limestone, containing small Gasteropods like Paludina and 

 fragments of 0?/rena-like valves, together with several black and 

 dark-brown, shining Ostracoda. Although met with where the 

 South Branch runs over the Belly-Eiver Beds ^ (Cretaceous),^ this 

 block was recognized as belonging to the Saint-Mary-Eiver Series, 

 as explained at 37 C of the " Geological and Natural-History Survey 

 and Museum of Canada, Eeport of Progress, 1882-3-4," 8vo. 

 Montreal, 1885, with maps. 



PoNTooYPRis, G. 0. Sars, 1865. 



3. PoNTOCYPRis PYRiFORMis, sp. nov. PI. II. Figs. 3a, 6, c. 

 Length "72, height '4, thickness '32 mm. 



Trigonal, pear-shaped, boldly-rounded in front, contracted to a 

 sharp point behind ; boldly arched on the dorsal and sloping with 

 a slight sinuosity on the ventral border, both meeting at an acute 

 angle posteriorly. Surface smooth, moderately and almost uniformly 

 convex, but slightly more swollen towai'ds the ventral region. 

 Probably of brackish- water habitat. One valve in blackish lime- 

 stone from an unattached block found at the South Branch of the 

 Milk Eiver, N.W. Territory. 



Among several published forms more or less resembling this in 

 shape, one variety of Eeuss's Oytherideis Icevigata (in Geinitz's 

 " Elbthalgebirge in Sachsen," 1874, p. 150, pi. xxviii. fig. 3) is 

 perhaps the nearest in shape, but it is not so pyriform, and is much 



^ These strata on the South Branch (Report of Progress, 1885, page 39 C) show 

 sandstones, with some ironstone ; and a few miles further down these are overlain by 

 greyish and blackish bedded shales and sandstones, with a carbonaceous layer ; and 

 in them, among some fragments of shells, JJnio was determined. 

 . 2 Ibid. p. 119 C. 



