

24 PBOF. T. E. JONES ON SOME PALEOZOIC OSTEACODA. 



Small, subtriangular, with the back straight, the ventral margin 

 strongly curved, giving ^reat relative height to the valve. 



In a fine-grained sandstone, calcareous and finely micaceous ; 

 from the Hamilton G tp, Ontario Co., New-York State. 



2. Lepeeditia (?) siNUATA, Hall. (PL I. figs. 12 «, h, c.) 



Leperditia sinuaia, Hall, ' Canad. Nat. & G.eol.' vol. v. 1860, 

 p. 158 ; and Dawson, ' Acadian Geology,' 3rd edit., 1878, pp. 609, 

 610. 



Size : length -99 mm., height -60 mm., thickness '48 mm. 



This is a small, black, shining Leperditia (?), subovate in outline, 

 being straight on the back and without distinct cardinal angles ; 

 semicircular behind ; boldly curved below, but rising with a less 

 bold curvature to the limited curve in front. Our specimen does 

 not show the minute tubercle, but the sinuous mark or little fold 

 on the postero-ventral border is present, and reminds us of a some- 

 hat similar feature in Beyrichia Mans, Boll, 1856. 



In a grey limestone with Erachiopods &c. from Arisaig, Nova 

 Scotia. 



3. Lepeeditia hudsonica, Hall. (PL I. figs. 5 a, h, c (after the 

 original drawings), and figs. 11 a, 6, c ; and PL III. fig. 20 ?.) 



Leperditia hudsonica, Hall, ' Palteont. New York,' vol. iii. 1859, 

 p. 375 (pi. Ixxix. a, figs. 7 «, h, c; not published). 



Length. Height. Thickness, 

 mm. mm. mm. 



r PL I. fig. 5 5-0 3-50 3-0 



Size \ I. fig. 11 -48 -36 -32 



[ III. fig. 20 (?)-46 '2Q 



Carapace small, symmetrical and very convex (subglobular), being 

 almost as thick as it is high, straight on the back, with the anterior 

 cardinal angle more developed than the other ; free margin (ventral 

 edge and two ends) well rounded, rather more than semicircular; 

 anterior extremity less truly rounded than the other. Further 

 exact description is given by Prof. Hall (l. c), especially that the 

 right overlaps the left valve. His specimen came from the base of 

 the Lower-Helderberg Group, at Becraft's Mountain, near the 

 Hudson. 



A very similar, if not identical, form has been sent to me by 

 Prof. Whitfield for examination. This, of very much smaller size, 

 is shown by figs. 11 a, 6, c, taken from two little subglobose valves, 

 somewhat pustulose towards the curved edge. Excepting the granu- 

 lation there is apparently nothing to separate them from L. hud- 

 sonica. They occur on a piece of limestone (*' 500 <i"), consisting 

 of Crinoidal joints, Brachiopods, Polyzoans, &c., and belonging to 

 the Hamilton Group (Devonian) ; at Eighteen-mile Creek, Lake 

 Erie Shore, New-York State. 



