481 



Obol. 



Billings, Eeport of Progress, Canada Survey. 1857, Black river 

 group.) Geol. Can. 1863, page 142, figs. 75 a^ dorsal view 

 showing area of ventral valve ; 5, side view ; c, dorsal valve of 

 broad, oval variety. Trenton II c. 



Obolus ? Found by Emmons in the white, friable 



shales of Virginia, with Lingula striata^ 

 Orhicula excentrica^ &c. Am. Geol. I, ii, p. 

 113, pi. 1, fig. 10.— /f G ? The age of these 

 shales are unknown to me. 



Obolus ? Rogers, page 817. — Potsdam formation ; 



probably one of the Oholellas^ or Kutorginas. The same is 

 probably true of Owen's undetermined Oboli. — I? G ? 



Odontocephalus selenurus. See Dalmanites selenurus. 

 Villa. 



Odontopteris ajinis. Lesquereux, Coal Flora of Pa., Vol. 



3, 1884, page 742, plate 97, fig. 4. Rare, in Mazon creek nod- 

 ules. 111.) Collett's Indiana, 1883, page 54, plate 11, fig. 1; 

 close to Odontopteris subouneata. — Coal measures, XIII 



Odontopteris brardii. Found in the Darlington bed at 

 Cannelton, Beaver Co., Pa. M, 54. — XIII 



Odontopteris britannica. Gutbier, Abdr. p. 68, plate 9, 

 figs. 8 to 11; Weiss, Flor. Foss. plate 1, fig. 2. Lesquereux 

 found exactly similar specimens (quite unlike 0. schlotheimii., 

 to which Schimper refers 0. Irit) at Cannelton, Pa., and St. 

 Clairsville, Ohio, in Lacoe's collection at Pittston, Pa. Kit- 

 tanning group of Allegheny river coal series. — XIII 



Odontopteris gracillima, Newberry. Pal. Ohio, Vol. 1, 

 1873, page 382, plate 46, fig. 1, part of summit of frond ; 2, 



