In this condition there is a single orbital cavity in the middle line, containing, in some cases, only a rudiment of the eyeball (Fig. 9), in others a fully-developed globe, or it may be two, close together. There is no retina in the eyeball, which consists alone of parts developed from without. The cerebrum consists of one mesial portion, containing a single ventricle.

According to Cleland there is here a dropsy of the roof of the thalamencephalon, including the pineal body. The enlargement of these parts causes defect of the anterior cerebral vesicle, and by its pressure also interferes with the development of the face.

Encephalocele in median section.

Fig. S. - Encephalocele in median section. The diminutive cranial cavity has a wide communication with the sac, which contained a nearly full-sized brain. (W. I. M).