1905.] IN A CASrEATED PR0XC4BUCK. 193 



variations cleseiibed below to be due to castration, it is evident 

 that the operation has affected the horns in a very remarkable 

 manner. 



Description of the Horns. 



Instead of rising from the forehead as upright, laterally-com 

 pressed, bony prominences, the horn-cores bend obliquely forwards 

 in a vertical plane, their axes inclining to the plane of the fore- 

 head at an angle of about 45°. They are only about 2 inches long. 



The horn-sheaths cover the core to the root, becoming gradually 

 softer proximally, and passing into the hairy integument of the 

 head. They project nearly horizontally forwards in the direction 

 of the nose for a distance of about 3| inches, then curve down- 

 wards for about 2| inches, and then backwards towards the eye 

 for about 3| inches, the terminal inch curving lightly inwards 

 and downwards to a point close to the eye. Their total length 

 along the outer or convex curve is thus about 9^ inches. They 

 also present a spiral twist forming about one-foui'th of a complete 

 turn. This is attested by the fact that an interfibrous groove 

 starting in the middle line of what is morphologically the posterior 

 surface of the base, but which by the change in the direction of 

 growth has become secondarily the upper or dorsal surface of the 

 horn, gradually passes on to its inner surface to terminate on the 

 concave side of the apically curved portion, this concave area 

 being also, morphologically, although it faces the middle line, 

 part of the posterior surface of the horn, as is abundantly proved 

 by the recurvature of the apex of the normally formed horn. 

 The same extent of torsion is further shown by the lateral 

 compression of the base of the horn being replaced by dorso- 

 ventral compression towards the apex, the normal horn being 

 laterally compressed throughout. Briefly stated, the result of the 

 twist is to make the distal half of the posterior surface of the horn 

 face the middle line of the body. 



Although the horn-sheaths have been described above as if 

 each corresponded to a single fully-formed horn-sheath of an 

 adult Prongbuck, closer examination shows that they are in 

 reality composite — that is to say, they consist of a series of horn- 

 sheaths partially severed from each other. The exact number of 

 sheaths involved in the formation of the whole is not easy to 

 determine. There appear, however, to be six. In the right 

 sheath, the outer or convex side shows a continiious and unbroken 

 surface except at two points, the proximal break occurring at 

 about I of an inch from the base, and the distal a little more 

 than 2| inches from the apex ; there is, however, a partial break 

 li inches behind the distal break. These three breaks are continued 

 round the horn on to its convex side, and very evidently represent 

 the proximal ends, formerly extending to the root of the hoi-n-core, 

 of three separate sheaths. Moreover, on the concave side there 

 are two additional breaks in the continuity of the tissue which 

 extend onlvhalf round the sheath, one situated at about 1| inches 



13* 



