NATURAL SCIENCES OF PHILADELPHIA. T5 



I 



Dinosaurian, though they may have belonged to a mammalian." 

 I ma}' add that, on p. 8, Prof, Cope, quoting from the same Pro- 

 ceedings, p. 89, indicated that I had referred Ischyrotherium to a 

 Sirenian. This is so, but Prof. Cope appears to have overlooked 

 the more full account of the animal in the Trans, of the Am, Phil. 

 Soc, 1859, p. 151, in which, though I still refer it with doubt to 

 the mammalia sirenia, I state that the remains may have belonged 

 to an aquatic reptile. 



In view of the reptilian character of Ischyrotherium, Prof. C. 

 has changed the name to Ischyrosaurus, but his reason for doing 

 so appears to me not to be valid, as classical authorities at times 

 have included reptiles in the word therion, and it has been con- 

 sidered admissible as applied to the extinct Cheirotherium. 



April 21. 

 The President, Dr. Ruschenberger, in the chair. 

 Eighteen members present. 



Note on the Enemies of Diffliigia. Prof. Leidy remarked that 

 in the relationship of Difflugia and Amcjeha we would suppose 

 that the former had been evolved from the latter, and that its stone 

 house would protect it from enemies to which the Amoeba would 

 be most exposed. The Difflugia had many enemies. I have 

 repeatedly observed an Amoeba with a swallowed Arcella, but 

 never with a Difflugia. Worms destroy many of the latter, and 

 I have frequentl}' observed them within the intestine of Nais, 

 Pristina, Chaetogaster, and ^olosoma. I was surprised to find 

 that Slentor polymorphus was also fond of Difflugia^ and I have 

 frequently observed this animalcule containing them. On one 

 occasion I accidentally fixed a Stentor by pressing down the cover 

 of an animalcule cage on a Difflugia.^ which it had swallowed. 

 The Stentor contracted, and suddenly elongated, and repeated 

 these movements until it had split three-fourths the length of its 

 body through, and had torn itself loose from the fastened Difflu- 

 gia. Nor did the Stentor suffer from this laceration of its body, 

 for in the course of several hours each half became separated as a 

 distinct individual. 



Bemarks on a supposed Compound derived from Leather. 

 Prof. Leidy directed attention to a dark-red, compact, sliining, 

 resinous-looking mass, several inches in thickness, which, he said, 

 was reputed to have been derived from leather in the great fire of 

 Chicago. It now exhibits no evidence of organized structure, 

 and its origin would not have been suspected from its appear- 

 ance. On burning it still gives out the peculiar odor of burning 

 leather. It was supposed to be a compound evolved from the 

 leather, under the influence of high heat with absence of air. 



