1905-6. 
Professor Ewart on the Tar pan. 
7 
The Tarpan and its Relationship with Wild and 
Domestic Horses. By J. C. Ewart, M.D., F.R.S., 
Regius Professor of Natural History, University of Edinburgh. 
(With Three Plates.) 
(Read November 6, 1905.) 
In December 1902, 1 communicated to the Society a preliminary 
note “ On a New Horse from the Western Islands,” 1 and six months 
later submitted the results of experiments made with a view to 
ascertaining whether Prejvalsky’s horse is a true wild species, or, 
as suggested by Flower and others, a chance hybrid between a 
kyang and an escaped Mongol pony. 
The new horse (now commonly known as the Celtic Pony) 
described in the first paper is characterised by a small head, large 
prominent eyes, short ears, and narrow nostrils ; by a long tail, 
mane, and forelock, and, during winter, by a thick, light yellow- 
dun woolly undercoat and a remarkable tail-lock (PI. II. 7) ; by 
having, like Prejvalsky’s horse, only 23 dorso-lumbar vertebrae, 
and also by the complete absence of callosities from the inner 
aspect of the hocks and from the region of the fetlocks — i.e. by 
the absence of the hind warts or chestnuts, and of the four ergots 
invariably present in typical specimens of the common horse. In 
speed and staying power, intelligence and docility, the Celtic pony 
takes after liigli-caste, fine-tempered Arabs. 
This new horse I provisionally named Equus caballus celticus ; 
but as it — apart from its coat — more profoundly differs from the 
common horse than either asses or zebras, it will probably be 
eventually regarded as a true species. The results of the experi- 
ments with the wild Asiatic ass submitted in the second paper 2 
made it sufficiently evident that Prejvalsky’s horse is not a 
hybrid between a kyang (E. hemionus ) and a Mongol or other 
Eastern pony. Further observations have made it equally evident 
that while some of the horses found running wild amongst the 
Great Altai Mountains may count strayed domestic horses amongst 
1 Nature , vol. lxvii. p. 239, 1903. 
2 Proc. Royal Soc. Edin. , 1903, pp. 460-8. 
