438 



Mr. E. T. Newton. On the Skull, $c, of [Mar. 22, 



and about as thick as it is wide. The olfactory lobe is small. 

 Behind the cerebrum is a pair of large optic lobes, occupying a 

 prominent position on the sides of the brain, and extending: upwards 

 well to the upper surface, but not meeting above in the middle 

 line/ The region of the cerebellum has been broken away, and 

 its exact form therefore is somewhat uncertain; but judging from 

 portions which remain, it is tolerably clear that it extended between 

 the optic lobes, and may have reached as far forwards as the cere- 

 brum. Attached to the side of the medulla oblongata is a large 

 flocculus, such as occurs in this position in birds. 



It was the finding of the flocculus which led to the discovery of 

 some parts of the auditory apparatus. On clearing away the stone 

 in this region, a small tube filled with matrix was found arching 

 over the pedicle of the flocculus and dipping down between it and the 

 optic lobe. This tube occupies the position of the anterior vertical 

 semicircular canal in the goose. By tracing the canal backwards 

 and downwards it was found to join another similar tube forming an 

 arch behind the flocculus, that is, in just the position of a posterior 

 vertical semicircular canal. By careful excavation below the floccu- 

 lus, a portion of a third tube was found, arching outwards in a 

 horizontal plane, and this is believed to be the external semicircular 

 canal. 



The similarity between the base of the fossil skull and that of the 

 Chameleon led to the inference that the fenestra ovalis would be 

 found to be similarly placed in both, and by clearing away the matrix 

 from the orbit and temporal fossa this inference was proved to be 

 correct. The form and relations of the quadrate bone make it highly 

 probable that this Pterosanrian had no ear-drum. 



A comparison of this fossil with the skulls of known Pterosauria, 

 leaves no doubt that it is more nearly related to the Scaphognathus 

 (Pterodactylus) crassirostris than to any other species, but as it differs 

 from that form, and is evidently new, it is to be named specifically 

 Scaphognathus Purdoni. 



The Pterosaurian skull, as exemplified by this Lias fossil, resembles 

 more the Lacertilian than any other type of Reptile skull ; and seeing 

 that the skulls of birds and lizards are in many points very similar, 

 one is not surprised to find in this fossil characters which are also 

 found in both these groups. In considering, therefore, the relation 

 which the Pterosaurian skull bears to those of birds and lizards, the 

 characters should be especially noticed which serve to distinguish 

 between the two groups, thus : — 



1. In birds the brain-case is larger in proportion to the size of the 

 skull than it is in lizards. 



2. The quadrate, pterygoid, and palatine bones are movable on the 

 skull in birds ; but more or less fixed in lizards. 



