68 ABNORMAL CONDITIONS OF THE AXIS. 



b. Occipital deficiency. 



278. The skull and vertebral column, with a portion of the ribs and 



the pelvis, of a hydrocephalic male foetus, with distortion 

 of the vertebral column, defective development of the oc- 

 cipital bone, and defective closure of the vertebral canal 

 behind. 



The laminae of the cervical and first six dorsal vertebrae are 

 widely separated behind ; those of the right side are defective. 

 There are apparently but five cervical vertebrae, and their laminae 

 are fused together. The head was pressed back so that the edges 

 of the enormously dilated foramen magnum rest on the edges of 

 the laminae of the dorsal and cervical vertebrae, to which they were 

 attached by ligament. The supraoccipital cartilage bones are very 

 small. There are, however, two scale-like bones representing the 

 upper part of the supraoccipital bounding the foramen magnum 

 above. The frontals and parietals are very large. There is spina 

 bifida in the lumbar and sacral region. The pedicles and laminae 

 are well developed, but they are spread out on either side, so that 

 the spinal canal is open behind. There was talipes of both feet. 

 Presented by J. Hutchinson, Esq., 1870. 



279. An occipital bone with similar deficiency from a Human 



foetus. 



c. Epicephalocele. 

 Syn. Monstres Exencephaliens, Geoff. 



280. A Human female foetus with a large cyst-like tumour in the 



occipital region. The frontal bones are much depressed. 

 The cyst has been opened behind ; the posterior part of 

 the cerebrum protrudes into it. 



281. The head of a Human foetus with a large epicephalocele on 



the vertex. Hunterian. 



Subclass III. Anencephalus. 

 Syn. Monstres Pseudencephaliens et Acephaliens, Geoff. 



In anencephalus the roof of the skull is absent or consists of the 

 membrane-bones pushed forward upon the forehead, where they 

 form a narrow band or crest ; the cartilaginous supraoccipital is 

 always absent, and the whole base of the skull is widely exposed. 

 The neural arches of the cervical vertebrae are more or less open, 



