SILURIAN OSTRACODA. FROM XORTH AMERICA, ETC. 549 



slopes, with a hollow curve, down to the postero-ventral angle ; 

 rounded in front and terminating in a sharp triangular process 

 of the ventral border behind. Thus it approaches Bairdia, espe- 

 cially such forms as were ascribed to that genus in 1879 (' Quart. 

 Journ. Geol. 8oc.' vol. xxxv. pp. 572 et seq. pi. xxix. figs. 11-16, 

 and pi. xxxi. figs. 1-7). None of these Carboniferous valves, how- 

 ever, quite match our figured specimen. Bairdia Griffithiana., 

 Jones & Holl, ' Ann. & Mag. Nat. Hist.' July 1868, p. 58, pi. vii. 

 fig. 10, from the Lower Silurian of Ireland, is not far removed, but 

 is much shorter, higher, and blunter. 



Prom the lowest Division of the Anticosti Group (Cincinnati 

 Formation, Dr. Hinde), at English Head, Anticosti. Several speci- 

 mens of single valves, together with numerous other Ostracoda, lie 

 on the bed-plane of a compact grey limestone, probably composed 

 of similar organisms. Coll. Dr. U. J. Hinde, P.G.S. 



The edges of the valves are in general so much concealed by the 

 matrix that it is difficult to define many of the individuals. There 

 is an undetermined Leperditia among them. 



XII. Macrocypris, G. S. Brady, 1867. 



20. Macrocypris ? subcylindrica, sp. nov. (PI. XXI. figs. 5 », 5 h.) 



Length 1*6 mm. ; height -5 mm. : thickness '6 mm. 



Pig. 5 .is a long, convex, smooth, right valve of a subcylindrical 

 carapace, nearly straight above and below, but higher behind, and 

 with oblique ends, one more so than the other. Nearly straight 

 above for four-fifths of the dorsal edge, and then sloping down with 

 a very gentle curve to the obtuse postero-ventral angle. Straight 

 below. Ends oblique ; subangular behind ; the front end narrow, 

 with a short oblique curve bending downwards and backwards. 



It is somewhat like Macrocypris silir/uoides, Jones, 'Ann. &Mag. 

 Nat. Hist.' 1887, ser. 5, vol. xix. p. 194, pi. v. fig. 9, which is 

 arched on the back and rather sharper at one end than the other ; 

 and also somewhat near M. symmetrica, op. cit. p. 181, pi. vii. fig. 8, 

 which is blunt at the ends and with nearly equal edges : the speci- 

 mens under notice are very much narrower than either. As the 

 two Macrocyprides referred to above offer the nearest analogies, 

 I place this species also in Macrocypris. 



This species occurs in some numbers with Bairdia anticostiensis, 

 &c., at English Head, Anticosti. 



X. Bythocypris. (See page 548.) 



21. Bythocypris? obtusa, sp. nov. (PI. XXI. figs. 4 a, 4 6.) 



Length 1-8 mm. ; height I'O mm. ; thickness -9 mm. 



This suboblong form is very near to Bythocypris symmetrica, Jones, 

 op. cit. 1887, p. 181 ; but, being much blunter in front, has almost 

 equal ends. 



With Bairdia anticostiensis, &c., in limestone of the Cincinnati 

 Group, at English Head, Anticosti. Coll. Dr. G. J. Hinde, F.G.S. 



