COPE ON GEOLOGY AND VERTEBRATE FOSSILS. 591 



la none of the European crania is the snpraoccipital region directed 

 obliquely forward as in the Diclonius, but the lateral constriction is seen 

 in Dr. Seeley's specimen. 



It is then possible that the bone which I have called a downward pro- 

 longation of the exoccipital is the prootic, although I cannot certainly 

 detect any suture separating it from the former. In that case, the large 

 foramen in front of it becomes the foramen ovale, the bone in front of it 

 the alisphenoid, and the anterior foramen the foramen opticum. In view 

 of the form of the brain, this identification is not without probability. 



The cast of the brain does not display any median fissures. Its vertical 

 depth is greatest a little anterior to the, foramen magnum, where it is com- 

 pressed, the sides being shallowly concave, and separated from the 

 superior surface by a longitudinal angle. In front of this position, it is 

 subcylindric and the anterior extremity comes to an obtuse termina- 

 tion, which is convex in cross-section and concave in the vertical sense, 

 the lower portion continuing downward and forward, possibly to the 

 hypophysis. 



Before describing the remaining cranial bones, the significance of the 

 characters above recorded may be considered. As regards the form of 

 the brain, the superior elevation of the posterior region above the ante- 

 rior is a point of resemblance to Birds rather than to Reptiles ; the ap- 

 parent absence of prolongation of the hemispheres into the olfactory 

 lobes is also a character of Birds rather than of Eeptiles. The brain- 

 cavity is in fact closed in front aboNe, as in Mr. Hulke's skull already 

 mentioned, which ahso presents no prolongation for the olfactory lobes. 

 This is present even in those Reptiles where the chamber is closed in 

 front, e. g. OpMdia, while it is absent in Birds. When viewed from above, 

 there are other affinities indicated. The absence of indication of lateral 

 optic lobes points to Reptiles and not to Birds, while the small diameter 

 of the hemispheres is not like either class, but resembles more the state 

 of things in Batrachia and Fishes. The characters of the osseous struct- 

 ure present some Avian affinities. Such are the simple, semiglobular 

 occipital condyle, the infero-posterior processes of the basi-occipital, 

 and the short thin lateral processes of the exoccipital bones. The great 

 prolongation of the basispheuoid, the lack of lateral processes of that 

 bone, and the absence of overhanging lateral margin of the superior 

 cranial walls may be looked upon as Ophidian or Avian characters. La- 

 certilian characters are completely wanting. The anterior termina- 

 tion of the brain-case and its basis resembles nothing else. 



In close contact with the side of the mass above described was found 

 a bone of peculiar form, which doubtless belongs to the suspeusoriura. 

 There could be no doubt of this were the bone suturally united with 

 the cranial element proper. It is, however, only applied to it by the 

 intervention of a body of hardened matrix, of the peculiar color of that 

 which occupies the cranial chamber, and which differs much from the 

 lignite in which I found the bones imbedded. Almost in contact, I 



