67 



dominant type of the Potsdam should occur in such a horizon appears to 

 me to be a most extraordinary fact. Judging from the fossils alone, I 

 should say that the L^vis formation immediately succeeds the Calciferous, 

 but the physical evidence seems to show that such is not the case. 



2. — Descriptions of New Species of Fossils. 



In a paper published in the Canadian Naturalist and Geologist, vol. v, 

 p. 201, August, 1860, I made a provisional division of the specimens in 

 which the fossils were first found at Point L^vis, and designated them 

 simply as limestones Nos. 1, 2, 3 and 4. I think it advisable to retain 

 these divisions here, but it is quite clear that they all belong to the same 

 series of beds. No. 1 is a peculiar greyish-white limestone and holds a 

 number of species that have not been discovered in any locahty except at 

 Point Levis. Sir W. E. Logan has shown that there are nme bands of 

 the limestone and that my Nos. 1 and 3, belong to his band No. 3, and 

 also that his No. 4 includes my No. 2. There are sevei-al species common 

 to these two bands, but a great deal more must be done in the way of col- 

 lecting fossils at Point Levis before all the questions that have arisen with 

 regard to the fauna of that locality can be satisfactorily disposed of. 



The following is Meek and Hayden's description of Oholella nana. 

 " Obolella nana." (Meek and Hayden.) 



" Shell very small, subcircular, or transversely suboval, moderately con- 

 vex, rather thick ; front broadly rounded ; sides more narrowly rounded. 

 Beak of dorsal valve short and obtuse. Ventral valve proportionally a 

 little longer than the other, about as long as wide, and having a slightly 

 more prominent beak ; without a distinct mesial ridge within ; scars of 

 adductor muscles ? located behind the middle and diverging towards the 

 front. Surface marked by a few concentric furrows ; exfoliated specimens 

 showing small obscure regularly disposed radiating strise on the inner 

 laminae. 



" Length of dorsal valve, 0-15 inch ; breadth of do., 0-17 inch ; con- 

 vexity, 0-15 inch. Length and breadth of ventral valve of a smaller spe- 

 cimen, each 0-14 inch. 



" In first sending on to the Academy a description of this little shell, we 

 had referred it Avith doubt to the genus Obolus, stating, at the same time, 

 that its muscular scars, so far as they could be made out from the only spe- 

 cimen we had seen showing the interior, seemed to present diftbrences from 

 the type of Eichwald's genus. Since seeing Mr. Billings's figures of his 



