82 



In America we have, below the L^vis, and therefore below the LoAver 

 Llandeilo, a large number of species of Gasteropoda and Cephalopoda. 

 Many of these are undescribed, but taking all into account, I think there 

 must be at least 40 Cephalopods and 80 Gasteropods in the Potsdam and 

 Calciferous. Some of these are of large size, and in many localities the 

 strata are crowded with the individuals. In England there are only 3 or 

 4 rare and small species known below the Lower Llandeilo. Among the 

 other fossils there are no species common to England and America unless, 

 indeed, some of the GraptoUtes. We have thus, as yet, scarcely any 

 facts upon which we can safely proceed to parallel these ancient deposits 

 with each other, although there can be little doubt but that, in a general 

 way, the English series may be placed opposite that of America. 



The same dij0&culties arise with regard to the Upper Llandeilo. This 

 formation has been paralleled with the Trenton with which it possesses 

 scarcely any paloeontological character in common. According to the list 

 pubhshed in 1859 by Sir R. I. Murchison (Siluria, p. 632-552), there 

 are in the Llandeilo no Zoophyta of the group Zomitharia 7'ugosa ; —no 

 Echinodermata of the orders Crinoidece^ Cystidece, Asteridce or JEdrioas- 

 ieridce; — no species of Rhynchonella ; — none of Strophomena ; — only 

 three small species of Lamellibrancliiata ; only 1 Gasteropod ; — 2 Sete- 

 rojyods, and 4 Cephalopods. The trilobites are all, with the exception of 

 Calymene Blumenhachi and Trinucleus concentricus ? specifically and to 

 the extent of one-half generically distinct from those of the Trenton. The 

 only other fossils common to the two formations are Stenopora fibrosa, 

 Halysites catenulatus, Leptoena sericea, Orthis striatula f and 0. lynx. 

 These are all species of great geographical and geological range. With 

 such great differences and so few resemblances it is scarcely possible to 

 parallel the Llandeilo with the Trenton. It seems more probable that it 

 should come in somewhere between the Chazy and L^vis formations. It 

 has been often urged that such diversities as these may be due to differ- 

 ences in the character of the sediment. But I do not attach a great deal 

 of importance to that suggestion. For example, the trilobites of the Cono- 

 coryphe and Dikelocephalus group above alluded to are found in vast 

 numbers in Minnesota and Wisconsin in a formation of sandstone ; at Point 

 L^vis, in Canada, in a pure limestone, and in England in a formation of 

 slate. 



NEW SPECIES OF FOSSILS FROM THE CLINTON AND NIAGARA FORMATIONS. 



CEPHALOPODA. 



Genus Orthoceras, Breynius. 



0. Oberon, n. sp. — Shell of the medium size, tapering at the rate of a 

 little more than one line to the inch ; section circular ; Septa deeply 



