116 PHYSIOLOGICAL SERIES. 



ORNITHOSAURIA. 



D. 133. A cast of the cranium and parts of the cranial cavity of a 

 Pt.-rodactyl (Scapliognathus purdoni). The brain in this 

 creature appears to have entirely filled the cranial cavity. 

 It was of an essentially Avian type. The hemispheres 

 were large and oval longer and narrower than in most 

 Birds, but rounder anteriorly than in recent Reptiles. 

 They extended well back over the thalamencephalon and 

 partially covered the optic lobes. The latter were enor- 

 mously developed forming the broadest part of the brain, 

 and occupied the usual Avian position upon the latero- 

 ventral parts of the mesencephalon. In Birds this position 

 is due to the thrusting aside of the optic lobes by the 

 -ivat forward development of the cerebellum. Thus it is 

 legitimate to infer from the position of the optic lobes that 

 in this creature the cerebellum was strongly developed, 

 although it is not represented in this cast. 



DINOSAURIA. 



D. 134. The cast of the cranial cavity of a Dinosaur (Igiianodon 

 mantelli). The description of the brain from such a cast 

 as this must of necessity be to a large extent a matter of 

 inference ; for although the anterior and lateral parts of 

 the cranial cavity seem to have approximately followed 

 the contours ot the brain, such was evidently not the case 

 in the mid -dorsal region. 



The brain as a whole was long and narrow, with no very 

 marked ventral flexure of the medulla. The hemispheres 

 were peculiarly short and broad, and remind one mon- of 

 those of a Bird than of a Reptile, being shorter ami more 

 abruptly tapering in front than even in the Crocodiles. 

 They were strongly arched above, extremely prominent in 

 their lateral parts, and flatfish below. In the mid-line in 

 front they were prolonged into cither olfactory peduncles 

 or bulbs, it is not apparent which. 



The optic chiasma and infundibulum are strongly marked. 

 The space between the dorsil parts of the cerebrum and 

 the crest of the cerebellum shows no brain contours, as 

 evidently here the brain did not reach the cranial roof. 



