NATURAL SCIENCES OP PHILADELPHIA. 127 



had the leaves so much like the Quercus Cerris of Europe, that 

 branches of the two mixed together could scarcely be separated; 

 others came near in their resemblance the European Quercus 

 robur ; and again some near Q. alba of our own country. Did these 

 species grow there, we should assuredly have the remark by the 

 esteemed author of the " Manual." " Probably a hybrid between 

 Q. cerris and Q. alba." It was only after many successive days 

 of acquaintance with it, during which it had ranged from a low 

 bush to a small tree from leaves deepl}' lobed to leaves almost 

 entire from leaves of a deep shining green to leaves of a glau- 

 cous gray trees with fruit pretty well matured, to others only 

 just commencing to set their fruit from long to short peduncu- 

 lated, elongated to sub-rounded fruit and so on through other 

 changes that he was forced to the conclusion that he had but 

 one species to deal with, and such he believed would be the con- 

 clusion of any eareful botanist. 



Whatever may be ultimately accepted as the correct theory of 

 evolution, the fact of evolution so great as to produce forms equal 

 to the most decided species could scarcely be disputed ; and this, 

 too, as such cases as this of Quercus Douglassii proved, entirely 

 removed from the hand of art, or the agency of hybridization. 



May 28. 

 The President, Dr. Ruschenberger, in the chair. 

 Thirty-six members present. 



The following gentlemen were elected members of the academy: 

 Jos. H. Ogden, Jos. E. Gillingham, D. S. Holman, J. W. Miller, P. 

 P. Morris, and T. M. Drown, M.D. 



Mons. E. Riviere, of Menton, France, w r as elected a correspon- 

 dent. 



On favorable report of the committees, the following papers 

 were ordered to be printed. 



Permission having been granted, Prof. Cope exhibited some 

 vertebrae of a Plesiosauroid reptile and those of a smaller species, 

 probably a Glidastes, which were found in close proximity near 

 Sheridan, Kansas, by Joseph Savage, of Leavenworth. According 

 to this gentleman, the vertebral column of the Glidastes Was found 

 immediately below that of the Plesiosauroid and in a reversed 

 position, as though it had been swallowed by the latter or larger 

 reptile. The largest vertebrae of the Glidastes were about three- 

 quarters the length and one-fourth the diameter of those of the 

 Plesiosauroid, and the animal must have furnished a large, or at 

 least a long, mouthful for its captor. The bones of the Glidastes 



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