NATURAL SCIENCES OF PHILADELPHIA. 103 



■while the rounrled tuberciilons condition is move ohvions above. 

 In two marginal plates, conspicuously tuberculated al)0vc, the 

 lower surfaces are perfecth' smooth. These prol^ably pertain to 

 a difTerent species. None of the plates exhibit scute impressions, 

 generally so evident in the eniydes. 



Anosteira ornaf.a was almost tlic size of tlie palm or middle 

 hand. A pygal plate measures about eleven lines in length and 

 breadth ; and its height or thickness in front is seven lines. An- 

 other plate from a younger animal measures al)OUt seven lines 

 long, eight broad, and four lines thick in front. 



Hybemys arenarius — The second turtle, almost as large as 

 our common Emys picta, is founded on two specimens ol)tained 

 by Prof. Hay den from a tertiar3' forjnation on Little Sa)id3- Creek. 

 The}^ consist of a marginal plate and tlie portion of a costal plate. 

 The bones are proportionatel}- tliicker than in our common emydes, 

 but like thein are smooth and deeply impressed by t)ie scutes. 



The marginal plate appears to be the ninth of the series. From 

 the groove of the costal scute impression it is directed quite as 

 abruptly outwardly as in any recent emys. Its peculiarity', upon 

 ■which I liave founded the genus, is a striking character. The 

 surfaces, separated hj the groove of the marginal scute impres- 

 sions, present each a half circular boss at the fore and aft borders 

 of tlie bone. Thus from this specimen we may infer that the 

 margin of the carapace was ornamented wdtli a series of hemi- 

 spherical bosses, each of which was situated in the position of, and 

 divided by the sutures of the marginal plates. The breadtli of 

 the specimen fore and aft and transversely is half an ijich. 



April 25, 

 The President, Dr. Ruschenberger, in the chair. 

 T^^\"enty-nine members present. 



The resolution to amend Art. 2, Chapter XI., of the By-Laws 

 by the addition of the following words : " If there is no quorum 

 at tliese meetings then the election may be held at the sulisequent 

 meetings," having been approved at two preceding meetings for 

 business, ■was finall_y adopted. 



The deaths of Mr. Benjamin Marshall and Prof. Charles M. 

 "Wetherill were announced. 



The followins: gentlemen were elected members: H.Crawford 

 Coates and B. F. Quimby. 



Professor Marsh, of Yale College, made a communication on 

 some new rei)tiles and fishes from the Cretaceous and Tertiary for- 

 mations. Nearly all the specin)ens described were discovered by 

 the Yale College scientific party during their explorations in the 

 Rocky Mountain region last summer. 

 187L] 



