90 PROCEEDINGS OF THE ACADEMY OP 



lower jaw of Symborodon does not possess any. He pointed 

 out that these animals had small brains, with few convolutions, 

 wliicli were separated by deep fissures occupied by thin bony 

 laraince, and that the falx and tentorium are well developed. He 

 pointed out the relatively small size of the brain, and that at 

 least half of the length of the cranium is occupied by enormous, 

 undivided frontal sinuses. Each of these communicates with the 

 nasal meatus by an elongate foramen, and enters the base of the 

 corresponding horn core. He stated that similar sinuses exist in 

 the cranium of Eobasileuft^ and enter the basis of the middle pair 

 of horns in the same manner. 



June 23. 

 The President, Dr. Ruschenberger, in the chair. 

 Twenty-one members present. 



On the Pelvis of Hadrosaurus. Prof. B. Waterhouse Haw- 

 kins, having completed his model of Hadrosaurus at Princeton 

 College, took the occasion to call the attention of the Academy to 

 his success in placing certain fugitive bones belonging to Hadro- 

 saurus, and also to its English cousin Iguanodon. It might lie 

 allowable to remind the meeting of the fact that in 1868, when he 

 had made and presented the restoration of Hadrosaurus now in 

 the museum, he then recognized the homologous character of 

 a bone described by Dr. Leidy in his monograph of the Cretaceous 

 Reptiles, to that which had become a fugitive bone in Iguanodon, 

 the English representative of Hadrosaurus. These bones had 

 been for many years appointed to the place of clavicles by Prof. 

 Owen and Dr. Mantel, of England. When Mr. Hawkins made his 

 large restoration of Iguanodon at the Crj'stal Palace, in 1853, 

 his first difficulty was to find room for these so-called clavicles in 

 his model, a task which he was obliged to abandon, as they were 

 twice the size which the natural arrangement of the limbs rendered 

 possible. A few days previous to his sailing for America he found 

 that Prof Huxle}^ had been studying the same problem of their 

 true position in the animal's body, concerning which he delivered 

 an address before the Royal Institution. Prof Huxley, on this 

 occasion, transposed the pseudo-clavicles from the pectoral to 

 the pelvic arch, where he arranged them either as pubic or ischiatic 

 bones, and placed them as in the ostrich and rhea. At the same 

 time this transposition was taken advantage of to suggest the 

 probability of Iguanodon walking on its hind legs, thus account- 

 ing for some of the larger forms of bipedal footprints, and justify- 

 ing the establishment of the new order Ornithosauria. On the 

 arrival of Prof. Hawkins in America, after studying Dr. Leidj^'s 

 description of Hadrosaurus, he found that Dr. L. had anticipated 



