60 



DICUANOCERA. 



always have rings showing the growth of the horns, and that such 

 rings arc not to bo observed on the horns of the Prongbuek. 



When Dr. Canfiekl says that " the horns drop off annually," and 

 observes to Dr. Spencer Baird, " To convince you of this singular 

 fact is my jjrincijjal object in making you this communication," he 

 only intended to say that the horny sheath of the horns fell. The 

 American hunters and Dr. Marsh must have intended the same, 

 though Dr. Bachman and M. Audubon were deceived by the vague- 

 ness of the hunters' words ; and even Dr. Marsh, when he added 

 " like the Deer," could only have intended to say that the case of the 

 horns falls annually, and not that the entire horn or antler falls, as 

 is the case with the Deer. 



The shedding of the horns of Ant'dope capra had been previously 

 noticed by Dr. Weiuland (Zool. Gart. 18G3, p. 255), who inciden- 

 tally speaks of it as of an abnormal formation ; and more exphcitly 

 by Hr. Martin (ibid. 1864, p. 254), who regarded the old shed horn, 

 still adhering to the toj) of the new one, as the new horn which 

 would gi'ow downwards to the base of the frontal bone. 



Mr. Bartlett, in the ' Proceedings of the Zoological Society ' for 

 1865, p. 718, gave a very interesting and detailed account of the 

 manner in which the horny case of the horn separates from the core, 

 and how the new horny case is formed between the inner surface of 

 the old case and the core. 



Mr. Bartlett, in this paper, endeavours " to prove that the Prong- 

 buck's affinities are closer to the genus Cervus," to which he thinks 

 " it is more nearly allied than to the Antelopes." Indeed he thinks 

 he is " able to show that the horns of the Prongbuek are a modifi- 

 cation of the horns of Cervus.'' 



In this view I think Mr. Bartlett is entirely mistaken, and that 

 this theory obscures the otherwise very interesting details which he 

 gives of the pecidiarities of this animal. 



In the hoUow-horned Ituminauts the bony processes of the frontal 

 bone, which form the true horns of this group of animals, are per- 

 manent, and are covered, in the Oxen, Sheep, Goat, and Antelopes, 

 with a horny case, which is increased in size as the core enlarges by 

 the addition of new laminfe of homy matter to the inner surface, 

 especially near the edge of the sheath. The Gii'affes, on the other 

 hand, have the same permanent cores, which are covered with a hairy 

 skin, like the rest of the body, which covers the horn during the 

 entire life of the animal. 



The horns of the Deer, with which Mr. Bartlett compares those of 

 the Prongbuek, on the other hand, are only developed at a certain 

 season of each year ; and while they are being expanded they are 

 covered with a soft velvety skin containing a large number of large 

 blood-vessels : these vessels become obliterated, and the skin falls 

 off when the horns are fully developed ; and at the end of the sea- 

 son the horns themselves fall off, leaving only a burr on the frontal 

 bones. 



Now in the Prongbuek the core of the horn is permanent, vascular, 

 and exactly like the core of the horns of the true hoUow-horned 



