DUPLICITY. 11 



There is a single median eye situated behind a triangular 

 opening formed by the fusion of two pair of eyelids. 



Hunterian. 



56. The skull of a similar Calf, in which the fission has extended 



somewhat further back, so that there are two distinct 

 median orbits. The median malar bones are fused into 

 a single bone j they support a small mass of bone, which 

 articulates by a very imperfect joint with the median 

 rami of the mandibles. The median rami of the mandi- 

 bles are united by suture, and are much thickened and 

 distorted. The base of the skull exhibits a single basi- 

 occipital and a bifurcated basis phenoid with its two 

 median alisphenoids united. The exoccipitals, supraoc- 

 cipital, and temporals are single, except that there are 

 traces of median squamosals. The other bones of the 

 head and face are completely double. 



57. A similar skull, in which, however, dichotomy extends as far 



back as the basioccipital. In this skull there are two 

 supraoccipital and a median external auditory meatus; 

 the periotic bones of the median ear are double ; both 

 faces are distinct and well formed. Hunterian. 



58. The brain of a Calf with anterior dichotomy, probably from 



No. 55. All the parts in front of the pons are double. 

 The pons, medulla, and cerebellum are single. 



Hunterian. 



59. A portion of the brain of a Calf double as far back as the 



foramen magnum, probably from the same animal as 

 No. 57. It is stated in Hunter's MS. dissections that 

 all the cerebral nerves were double, that the eighth pair 

 were double at their origin, but that the median eighth 

 pair became fused and terminated in their passage through 

 the skull in connective tissue. Hunterian. 



60. A portion of the skull and the brain of the Sheep with di- 



chotomy extending as far back as the basioccipital bone. 



61. The tongues, hyoid bones, larynx, trachea, and oesophagus 



of a double-faced Calf, probably from the same animal as 

 Nos. 55 and 58, dissected. The double hyoid arch has 

 its median cornua distinct, close together, and cartila- 

 ginous. The median pair of tonsils are seen fused to- 

 gether between the two tongues. It is stated in Hunter's 



