288 BRITISH MAMMALS 



of the Mediterranean fauna. The chevrotains, or tragulines 

 {Tragulidie), a most interesting group of primitive Ruminants,^ 

 extended their range in the Miocene and Pliocene Epochs as far 

 north and west as France, but no traces have been discovered 

 of their existence in England. That great group of monster 

 Ruminants, the giraffes, also left England outside their ex- 

 tremest range, so that the first family of true ruminating, 

 selenodont (and horned) Artiodactyles represented in the British 

 fauna past and present is the deer. 



Group: PECORA. HORNED ARTIODACTYLES 



The Horned Artiodactyles (among which a few species have 

 lost or have never developed horns) are usually divided into four 

 families, based on the structure of the excrescences growing on 

 the skull, which are loosely known as "horns," independently 

 of their substance. The most primitive of the four families, 

 perhaps, is that of the giraffes, in which bony projections grow 

 out from various points of the skull, but remain practically 

 separate bones. In the Giraffe genus these are merely covered 

 with skin and hair. In the newly discovered okapi it would seem 

 as though the extreme tip of the short bony projection was bare 

 of skin and hair, and might even be an independent ossicle.^ In 

 certain more extravagant extinct forms of the Giraffe family, such 

 as the Sivatherium^ these bony projections grew to a great size, 

 forked and branched ; and the larger of the projections were 

 probably covered with some sheath of hardened hair or of horn. 

 In the case of the next family, the Prongbucks, a curious and 

 complicated stage is reached. The male prongbuck grows a 

 permanent pair of bony " horns " from the top of the skuU, 

 and then these bony projections are covered and increased by a 



^ The Tragulids — even those existing at the present day — represent very 

 nearly the original stock from which the horned Artiodactyles {Pecord) 

 sprang, the base from which the giraffes, the prongbucks, the deer, and the 

 Oxen-Antelope-Sheep group evidently arose. 



"^ In which case we have a very interesting suggestion as to the way in 

 which the deer's horns began. 



