240 



Prof. H. G. Seeley. 



[Dec. 8, 



bones of the crocodile. Professor Huxley* figured the ventral aspect 

 of a Crocodilus acutus at about the close of embryonic life, in 

 which a considerable fibrous development was found anterior to each 

 pre-pubic bone. This condition varies with age. In a large adult 

 crocodile from Abyssinia, in the British Museum, the fibro- cartilages 

 anterior to the pre-pubic bones are united in the mesial line, ante- 

 riorly, so as to form one mass. A similar condition is seen in 

 younger specimens. And if such a structure were sufficiently ossified 

 to be preserved in a fossil state, it would closely reproduce the form of 

 the anterior portion of Mr. Beckles' fossil, while the marks of lateral 

 attachment in this part of the fossil correspond with the grooves for 

 the last pair of abdominal ribs. Therefore I regard this specimen as 

 probably representing in the Iguanodon the pre-pubic bones of 

 crocodiles, as well as the cartilage connecting them with the ribs, 

 which Huxley terms the epi-pubis. On its mode of attachment to 

 the pubis I offer no suggestion, and there is no evidence available. 

 But since the bone in crocodiles and Ornithosaurs is attached in the 

 region of the pectineal process, it is probable tha.t it is connected 

 with the extension of the pectineal process in Dinosaurs, which Pro- 

 fessor 0. C. Marsh has named the pre-pubis, and I would bring the 

 pubic bone in the Ornithischia into harmony with the process in 

 Crocodiles by suggesting that the distal part of the bone, like the 

 anterior process, is entirely absent, so that only the sub-acetabular 

 part, which supports the pre-pubis remains in crocodiles ; and I 

 suppose that if the pubis had been prolonged distally in the crocodile, 

 it might have included the foramen for the obturator nerve. 



If this interpretation of Dr. Mantell's undetermined bone should be 

 sustained, it would contribute a new and distinctive element to the 

 Iguanodont pelvis, as remarkable as the pubic modification in an 

 Ornithosaur or Crocodilian, and distinct from either. The evidence 

 from the fossil allies of crocodiles by no means demonstrates the 

 nature of what 1 have termed the pre-pubic bones, though it shows 

 that pre-pubic ossifications exist which cannot be confounded with 

 the pubis, which may resemble the Crocodilian bone in form and in 



* ' Boy. Soc. Proc.,' vol. 28, PI. 8. 



