ARREST OF DEVELOPMENT. 47 



into a single foramen. The mandible projects consider- 

 ably in front of the united maxillae. 



Presented by W. R. Gilbert, Esq. 



180. The brain of the same. The anterior cerebral lobes are 



completely fused together. Behind the cerebrum is a 

 large triangular space, corresponding to the third and 

 lateral ventricles ; the fornix is seen crossing this space. 

 The corpus callosum is completely absent. 



Presented by W. R. Gilbert, Esq. 



181. The skull of a similar foetal Lamb. The mandible projects 



more than in No. 179. 



182. The skull of a foetal Horse, with a large median orbit. The 



axis is entirely wanting in front of the basioccipital. 

 There are traces of a vomer between the solid pterygoid, 

 palatine, and maxillary bones, but there is no trace of a 

 nasal cavity. The mandible projects an inch and a half 

 beyond the maxilla. The cranial cavity is much con- 

 tracted, and probably only contained a cerebellum. 



183. A fetal Kitten with complete fusion of the eyes. 



Hunterian. 



184. A similar Kitten, with the thoracic and abdominal cavities 



laid open, to show the perfect condition of the internal 

 organs. Hunterian. 



185. The head of an hydrocephalic foetal Pig, with deficiency of 



the facial axis and fusion of the eyes into a single globe. 

 The vertex is occupied by a very large cyst. Hunterian. 



186. A Human foetus with similar deficiency of the cranio-facial 



axis and complete fusion of the eyes. The cerebro- spinal 

 canal has been laid open. The whole cavity has evidently 

 been occupied by a large water-cyst. The head is doubled 

 back on the contorted spinal column, so that its axis is 

 almost parallel with that of the vertebral column. There 

 is complete deficiency of the occipital region and extreme 

 spinal bifida. The preparation should be compared with 

 Nos. 278, 279. 



c. Anopia. 



In the following preparations the. deficiency extends still fur- 

 ther back ; the trabecular arch is entirely wanting ; and the eyes 

 are rudimentary or absent, although the orbit remains. 



