JONES. ] 



PALEOZOIC OSTRACODA. 



ST 



14 (1883) agree best with our fig. 6 a. Other forms described by- 

 Schmidt from the Eassian territory vary from oblong to subovate. 

 They were from the Upper Silurian dolomitic limestone near the 

 mouth of the Waschkina Eiver, in the Timantundra, bordering the 

 Arctic Ocean. 



It is difficult to discriminate the specimen under notice from Leper- 

 ditia labrosa, Jones (Ann. Mag. N. H., ser. 3, vol. I, 1858, p. 245, pi. ix, 

 fig. 13), belonging to the Calciferous Sandrock of Canada ; but in this 

 latter the marginal rim is wider and the convexity greater; audit 

 certainly indicates a very similar, and so far an analogous form having 

 existed in still earlier times. 



From the white limestone of the west side of Long Point on the east 

 side of Lake Winnepegosis, collected by Mr. J. B. Tyrrell in 1889. 



There is some resemblance in both Ij labrosa and the present speci- 

 men, fig. 6, to the drawing of a young individual of the Scandinavian 

 Jj grandis, Schrenk, given by Schmidt in the Mem. Acad. Imp. Sci., 

 St. P^tersbourg, ser. vii, vol. xxi, No. 2, 18^3, p. 10, fig. 6. 



lY. Leperditia Whiteavesii, sp. nov. 

 PL 12, figs. 11, 12, 13, 14, and woodcut fig. 6. 



Fig. 6. Leperditia Whiteavesii, nov. (Interior extremity damaged.) Che- 

 mahawin, Saskatchewan River. Magnified f. 



Length, (hinge-line), height, thickness. 



mm. mm. mm. mm. 



P). 12, fig. 11 12- (8- ) 8-? — 



fig. 12........ 13- (7-5) 9- 5- 



fig. 13 9-? (6-?) 6- 3-5 



fig. 14 10-? (6-5) 7- — 



Woodcut fig. 6 12-6 (8-6) 8-3 5-3 



Suboblong, rounded unequally at the ends (figs. 11 and 12), being 



