or. 



54 AMERICAN JOURNAL 



Observations on the Eocene Lignite Formation of the United 

 States: BY T. A. CONRAD. 



II 



II 



In this paper, our valued contributor discusses tlie extent 

 of a formation which has been discovered to occur extensively 

 in the United States, while possessing throughout its entire 

 extent fossils, which, taken in connection with the position of ii 

 the beds, and their appearance, prove them to belong to the II 

 Lignite Epoch of the Older Eocene. 



Several species of Mollusca, received by Mr. Conrad from the 

 Lignite of Shark River, Monmouth Co., New Jersey, prove to 

 be identical with species of the London Clay and Plastic Clay 

 of Europe, while one species, Aturia ziczac^ Sowb., he has re- 

 cognized not only in one of the Shark River forms, but also 

 in a species from Astoria, in Oregon, formerly described by 

 him in "Dana's Report on the Geology of the U. S. Expl. 

 Exped.,"as Nautilus angustatus. This, and other forms therein 

 described, were at that time supposed to be Miocene, but Mr. 

 Conrad was led to believe in their Eocene origin first through 

 the discovery of the identity of this species in its far extended 

 American and European localities. It will be seen by a paper 

 herein published, on Mr. Gabb's " Report on the Cretaceous 

 Mollusca of California," that Mr. Conrad has again recognized 

 this species in Aturia Mathewsonii, Gabb, and that he refers a 

 considerable portion of the species described by Mr. Gabb to 

 the Older Eocene. 



Some of the species from Shark River proved to be new 

 and were described and figured in the 3d No. of this Journal 



Descriptions of three new S/jecies of Exotic Uniones : BY 



ISAAC LEA. 



Unio WrigJitii, China. IT. rufofuscus, ? 



Unio tortuosus, China. 



Of the last, Mr. Lea remarks, that "This remarkable Unio 

 is the first which has been found possessing an irregular plane 

 of the margin and being inaequivalve. When looking on the 

 anterior end with the ligament above, the line of the opening 

 of the valves curves to the right. The beak of the left valve 

 is higher than that of the right, and projects anteriorly. The 

 left valve is, therefore, larger than that of the right, and the 

 weight differs — the left being 257 grains, and the right 242 

 grains. The. very remarkable perpendicular striee on the late- 

 I'al teeth of this specimen, if alwaj^s present in other individ- 

 uals, will demand its being placed in the genus Prisodon, Schu- 

 miickeT= Castalia, Lam. These striai are probably normal to 

 the species. Before Triquetra contorta, from China, was de- 

 scribed by me, none of us could have expected to see a mem- 



