270 Proceedings of the Eoyal Physical Society. 



pression, with the exception of a single small mesial canal 

 which ends blindly. The orbit is a single cavity, in which, 

 however, there are indications of an incomplete septum. 

 Thus there were two supra-orbital ridges connected with the 

 frontal bone, and from the middle line there is a slight ridge 

 in the roof, which extends as far back as the optic foramen ; 

 and the latter, though single, has a spicule of bone extending 

 part way across. Each half of the superior maxillary bone 

 presents a concave border at the anterior part of the floor of 

 the orbit, and in the middle line between them is a slight 

 prominence. 



(y.) Skull of sheep (kindly lent by Mr Brotherston, curator 

 of the Kelso Museum), to which reference has already been 

 made. The occipital, parietal, and temporal bones are all 

 normal; the two portions of the frontal bone are firmly 

 united in the middle line ; the ethmoidal fissures are absent. 

 Here, also, the two orbital plates are fused in the mesial 

 plane. The two halves of the pre-sphenoid are united, and 

 surround a single large optic foramen. The post-sphenoid is 

 normal in shape, but the body is smaller than normal. The 

 cranial cavity is well developed, and of considerable size. 

 The superior "maxillary bones are fused ; neither nasal pro- 

 cesses nor nasal bones are present. The pre-maxillaries are 

 also absent. The palate bones, as in the last specimen, are 

 fused in the median line, but are not ossified to the superior 

 maxilla. The peculiar twisting of the vertical plates of the 

 palate bones is well marked, the surfaces looking anteriorly 

 and posteriorly. With the internal pterygoid processes they 

 form the bony anterior wall of the naso-pharynx, and obli- 

 terate the posterior nares. As above indicated, there are no 

 traces of nasal bones in the macerated skull, nor are there 

 any impressions marking points of articulation on the frontal 

 bone ; hence there has probably been no proboscis over the 

 eye. Neither in the floor nor in the roof of the orbit are 

 there the slightest traces of any septum. 



The term " cyclopea," applied to the group of monsters 

 of which we have described various examples, is preferable 

 to Monopsia or Mon ophthalmia, for the latter names do not 

 suggest the important fact that the single eye occupies a 



