148 Miscellaneous. 



causes may generally be traced gaps in reefs, and waste places of 

 limited extent in those seas which especially abound in corals. Dana 

 has recognized the effect of warm and cold currents in the general 

 distribution of corals throughout the warmer seas ; and the fact of 

 the same influences being at work, and easily recognized, in the 

 waters surrounding the British Islands appears sufficiently interest- 

 ing to justify me in bringing the subject before this Society, 



MISCELLANEOUS. 



Pliocene Fossil Fauna of the Niobrara River, in Nebraska. 

 By Joseph Leidy, M.D. 



The researches of Dr. Leidy upon the Lower Miocene Fauna of the 

 Mauvaises Terres are well known through his important memoir on 

 the "Ancient Fauna of Nebraska," published in vol. vi. of the 

 'Smithsonian Contributions.' But the results of the geological 

 survey, by Dr. F. V. Hayden, of the Pliocene deposits along the 

 Valley of the Niobrara are less generally known. We have hitherto 

 deferred noticing them, in the expectation that a detailed memoir, 

 with illustrations, would have appeared on the subject by Dr. Leidy, 

 as in the case of the Nebraska fauna above referred to ; but as that 

 has not yet taken place, a brief account of the results may be of 

 interest. 



The following is a list of the fossil Mammalia discovered in the 

 Pliocene beds of the Nebraska, as determined by Dr. Leidy : — 



RuMiNANTiA. Hipparion(Hippotherium)speeiosum, 

 Merycodus necatus, Leid. Leid. 



Megaloraeryx niobrahensis, Leid. Merychippus insignis, Leid. 



Procamelus occidentalis, Leid. mirabilis, Leid. 



gracilis, Leid. Equus excelsus, Leid. 



robustus, Leid. (Protohippus) perditus, Leid. 



Merychyus elegans, Leid. Rodentia, 



medius, W. Hystrix (Hystricops) venustus, Leid. 



m^or, Ijeia. Castor (Eucastor) tostus, Leid. 



Carnivora. 



Cervus Warreni, Leid. 



MULTUNGULA. . 



T,v- T -J Leptarctus primus, Leid. 



Rhmoceros crassus, Leid. v I trt i i \- ^ j t j 



Elephas (Lueleph.) imperator, Leid. ^ ■ j '., 



^ ^ tr ' f Lams saevus, Leid. 



SoLiDUNGULA. tcmerarius, Leid. 



Hipparion (Hippotherium) oecideu vafer, Leid. 



tale, Leid. epicyon, Leid. 



The first point of general interest in the above list is the entire 

 absence of Edentate forms in the Niobrara fauna. The same ob- 

 servation applies to the Miocene fauna of the "Mauvaises Terres," 

 while Megatherium, Megalonyx, and Mylodon occur extensively in 

 the United States ; and the leading characteristic of the fossil fauna 



