NATURAL SCIENCES OF PHILADELPHIA. 91 



Prof. Huxley's transposition of the pseudo-clavicles, which he 

 suggested in the above-named description might more probably 

 represent the ischiatic bones of Iladrosaurus. While engaged in 

 the Central Park, in developing the external form of tiiis former 

 inhabitant of New Jersey, Mr. Hawkins found it necessary to 

 renew the whole question as to the component parts of the pelvic 

 arch of these giants, wliich he practically tested with casts from 

 the actual fossils, endeavoring to ascertain their true position 

 according to both Dr. Leidy's and Prof Huxley's views. In this 

 attempt he utterlj^ failed, finding it impossible to place these 

 fugitive bones in such relationship to the gigantic femur as would 

 enable either animal to make footprints similar to those found 

 both in England and America. This being the case at the moment 

 when the iconoclastic Central Park Commission declined allow- 

 ing the further prosecution of paleozoic studies in the Park, the 

 inquiry was not continued until the opportunity was afforded by 

 the trustees of the New Jersey College at Princeton, who desired 

 to possess for their new museum one of Mr. Hawkins's restorations 

 of an extinct animal of New Jersey. For this purpose they 

 selected Hadrosaurus, which enabled Mr. H. to again investigate 

 the true position of the bones in question, which he has finall}^ 

 placed as the analogues of the abdominal plastron-like supports, 

 found largely developed in the pelvic region of the alligator. 

 This position of the bones, when united with the bipedal carriage 

 of the body, suggested immediately an analogy between these 

 fugitive bones and marsupial bones of the Didelphidse. These 

 remarks were illustrated by Mr. Hawkins in his usual manner 

 by crayon drawings on the slate. 



Prof. Cope stated that he was still of the opinion that the evi- 

 dence derived from Lselops and Megadactylus rendered it neces- 

 sary to believe in the backward direction of these bones in Hadro- 

 saurus. 



Prof. Cope described a species of Dipnoan fish of the genus 

 Ctenodus from the coal measures of Ohio, based on specimens 

 placed in his hands by Prof. Newberry, as follows : 



The top of the head is covered with angular plates or scuta, 

 arranged in the following manner on the region presented. Two 

 s^'mmetrical scuta occupy the median line, one in front of the 

 other. One of these is a longish coffin-shaped hexagonal, with 

 the suture with the other concave. The latter is more ovoid, 

 broad and convex next the first mentioned, and somewhat more 

 contracted at the opposite extremity. Beyond this are two shields 

 joining by a straight suture on the middle line ; besides this one, 

 they have two concave sutures for scuta, at the farther end two 

 concave lateral sutures, and a straight one to the adjoining me- 

 dian scutum, whose suture is also concave. On each side of this 

 median plate is a large area surrounded before outwards, and 



