ARREST OF DEVELOPMENT. 53 



the total absence of the cranio-facial axis in front of the 

 basisphenoid bone. A bristle marks the external opening 

 of the pharynx. Presented by Sir E. Home, Bart. 



204. The tympanic bulla and the labyrinth of the left ear from 



the same. 



205. The head of a Human foetus about the end of the sixth 



month, with a single eye in the mesial line and conjoined 



tympanic bones. There is no vestige of the mandible or 



facial axis. 



A dissection from behind shows the cavity of the skull and 

 pjiarynx. The eye and ears are in front of the axis of the skull, 

 which is perpendicular instead of horizontal. The cranio-facial 

 axis is entirely deficient in front of the basisphenoid. The tongue 

 is well formed, and occupies the upper part of the pharynx. The 

 pharynx opens externally by spiracles communicating with the 

 external auditory meatus. 



206. The posterior portion of the skull and brain of the same. 



The section passes through the cerebellum, pons, corpora 

 quadrigemina, and a portion of the medulla and the 

 fourth ventricle. 



207. The lateral half of the head of a Human female foetus with 



entire deficiency of the facial axis, fusion of the eyes, 

 absence of the mandible, and approximation of the ears. 

 The pharynx opens by the aural passage, through which a 

 black bristle has been passed. A mass of cartilage 

 and several small masses of bone are seen beneath the 

 eye, representing in some degree the deficient facial 

 bones ; there is also slight curvature of the cranial axis 

 forwards. Presented by W. Squire Ward, Esq., 1863. 



208. A longitudinal vertical section of the head and neck of a 



foetal Lamb with complete fusion of the eyes and ears 

 and absence of all the other parts of the face. The ce- 

 rebral lobes are hollow, and all the axial structures of the 

 brain were fused in the median line. The pharynx opens 

 by the median external auditory meatus, which is entirely 

 removed from the auditory capsule. The tympani are 

 absent. A bent purple glass rod marks the passage. 



Hunterian. 



209. The opposite half of the same. Hunterian. 



