Cope] &*-V [April 5 



The vertebrae have been described elsewhere, but important additions 

 to our knowledge can now be made. There are mostly small intercentra 

 throughout the dorsal and caudal series, in the latter prolonged into two 

 processes below, constituting chevron bones. The transverse processes on 

 the dorsal and lumbar vertebrae are undivided, and on some of the dorsals, 

 the ribs articulate with the centrum as well. They are present on the 

 anterior but wanting on the posterior caudal vertebrae. In adults the neu- 

 ral arch is coossified with the centrum, and on the lumbar and sacral re- 

 gion the neural spines are greatly elevated, indicating the presence of a fin 

 like that of Basiliscns. In one of the allied speci'es the diapophyses of 

 three vertebras are vertically expanded for the attachment of the ilium, but 

 the centra are not coossified. 



The humerus in this genus is of remarkable character. Its proximal ex- 

 tremity is expanded and regularly convex, with the articular surface at 

 right angles to the sides of the bone, and not developing a head. There is 

 a strong deltoid ridge or tuberosity, not extending far from the head. The 

 shaft is much contracted, and the distal end is more expanded than the 

 proximal. It is flattened, and supports no condyle. Its outline is trans- 

 verse at the middle and truncate at each lateral extremity. A large supra- 

 condylar foramen pierces the basal part of the distal expansion near the in- 

 ner border. The opposite edge is strongly grooved longitudinally, the 

 groove being bounded in front by a prominent crest, which sinks just 

 proximad of the distal border. 



The ilium is a flat bone, which contracts downwards and forwards to the 

 pubis. The latter is something like the ilium in form, widening in the op- 

 posite direction, i. e. downwards and forwards. Its form is something like 

 that of the CrocodiUa, and it is uncertain whether those of opposite sides 

 unite below. The ischium is a remarkable bone. It is greatly produced 

 anteriorty and posteriorly to the acetabulum, in forming with that of the 

 opposite side, a keeled boat-shaped body, which at its superior middle por- 

 tion includes the inferior part of the acetabulum. In O. natalis, the anterior 

 apex is below the middle line of the pubes near their anterior border. In 

 the same species there is an additional small element between the ilium 

 and pubis on the superior side at their junction. The acetabulum is formed 

 by the interrupted junction of the three elements. 



The femur possesses no third trochanter, and the head and great tro- 

 chanter are not separated by a neck. The little trochanter is large, and 

 the condyles are well defined. The head of the tibia is expanded, and the 

 fibula is well developed at both extremities. The phalanges are mode- 

 rately elongate, and are depressed. The claws are curved and compressed 

 below. 



The various remains of this genus now in my possession, and especially 

 the skeleton of G. natalis, show that the determinations of various parts of 

 the skeleton made from isolated fragments from Illinois, were correct. 



Cf the general affinities of. this genus it is only necessary now to state 

 that my reference of it to the RhynrJwcephtdia is- confirmed. It differs 



