12 PROF. T. E. JONES OJST SOME PAL^IOZOIC OSTRACODA 



JBolIia symmetrica (rare). Prom the Niagara Group, Lockport, New- 

 York State. Given to me by Dr. James Hall, P.M.G.S. 



2. ^CHMiNA Btrnesi (Miller). (PI. III. figs. 9-11.) 



Leperditia Byrnesi, A. S. Miller, ' Cincinnati Quart. Journ. of 

 Science/ vol. i. 1874, p. 123, fig. 10. 



Length. Height. Thickness, 

 mm. mm. mm. 



Size^^^-^ 1-^^ -7 



Pigs. 10 & 11. . 1-06 -7 -3 (-43 with the spine). 



This species has oblong valves, unequally rounded at the ends, 

 and each valve bears a short oblique spine, with a short angular 

 sulcus or notch behind it, and this is succeeded by a swelling or 

 knob at the postero-dorsal angle. The rest of the valve is smooth 

 and moderately convex, sloping gently to the free border, which has 

 a very slight, unequal, marginal rim. 



The individuals are numerous, constituting a considerable portion 

 of a thin layer of small organisms (Leperditia hudsonica (?j, rare, 

 Encrinites, Brachiopods, Polyzoa, Annelid jaws, &c.), on a compact, 

 blue-grey limestone from the Cincinnati Group (Lower Silurian), 

 Cincinnati, Ohio. Given to me by Prof. E. W. Claypole some years 

 ago. 



YI. Genus Bollia, Jones and HoU. 



BoUia, J. & H. ' Ann. & Mag. Nat. Hist.' ser. 5, vol. xvii. 1886, 

 p. 360. 



1. Bollia symmetrica (Hall). (Not figured here.) 



Beyrichia symmetrica^ Hall, ' Palaeont. New York,' vol. ii. 1852, 

 p. 317, pi. Ixvii. fig. 16 (containing four figures not separately 

 numbered); Dana, 'Manual of Geology,' 3rd edit. 1874, p. 227, 

 fig. 452. 



Size : length about 1 mm. 



This is closely allied to Bollia lata, but the curved or horse-shoe 

 ridge is thinner, with a somewhat sharp ventral bend, and encloses 

 a much larger and wider subtriangular depression or sulcus than in 

 B. lata. The two other ridges, at the ends of the valves, curve 

 down to the ventral border. In the lower left-hand figure they are 

 thicker than the horse-shoe ridge ; and one appears to overhang the 

 margin, the other being distinct from the edge. In another (lower 

 right-hand) of the enlarged views, one barely touches the margin, 

 while the other is divided off from its end of the valve by a distinct 

 curved furrow. 



Prom the Niagara Shale of Lockport, N.Y. 



2. Bollia lata (Yanuxem and Hall). (PI. III. figs. 1, 2, 3.) 

 Agnostisi Sins'] latus, Yanuxem, ' Nat. Hist. New York ; Geology,' 



pt. iii. 1842, pp. 80, 83 (the species is mentioned here). 



Beyrichia lata, Hall *, ' Palaeont. New York,' vol. ii. 1852, p. 301, 

 pi. A Ixvi. figs. 10, 10 a, h and 10 d (not tigs. 10 c, 10 e). 



* The species is here referred to " Conrad in Vanuxem." 



