SCHWARZ — EUROPEAN" FOSSIL HORSES 
153 
by Pomel,. Ph. Thomas, Boule, and other French authors, and are in 
part from late Pleistocene deposits. There is, however, no doubt that 
everything found in continental Europe and especially in England is 
not more recent than early Pleistocene, about corresponding to the 
“first Interglacial'^ of Penck. 
The modern Arab thoroughbred shows all the main characters of 
this type which have been pointed out above; in addition it possesses 
only five lumbar vertebrae, a feature not hitherto corroborated in 
fossil material, the available skeletons being of a very fragmentary 
nature. But there is ample reason to believe from the facts known 
that it is from this type that the Arab, Barb, and the high-bred Orien- 
tal" races have been developed. Since it has been shown that E. 
sivalensis is distinct it becomes highly probable that the thoroughbred 
races have been bred from the North African race of Equus stenonis 
which in a wild state survived up to the human period. 
The second type, which should be known as Equus cahallus^'^ (includ- 
ing a very great number of names the exact status of which is not yet 
determinable), first appears in the Pliocene Red Crag of England and 
the upper (upper Pliocene) deposits of the Sivalik Hills and is still 
found in a wild state in Mongolia. From the oldest to more recent 
forms a gradual decrease in size seems to exist which leads from the 
large tooth from the Red Crag figured by Owen as E. plicidens and the 
coarse limb bones mentioned by LydekkeF^ as belonging to a very 
large species, to the small light-limbed horses of late palaeolithic and 
neolithic times and Przewalski's horse of Mongolia. It would appear 
that this evolution has not taken place in a continuous series in at 
least those parts of western Europe which underwent glaciation, had 
their fauna destroyed by the ice and only in ^Tnterglacial" and post- 
glacial times regenerated from districts where it had been preserved. 
This assumption would explain the gaps between the large preglacial 
E. c. plicidens^ the middle sized second stage {E. c. rohustus) and the 
small third stage of the E. c. spelaeus-przewalskii type. At present 
only in one case^^ have transitional stages been described, and these 
Fixed by Ewart (Trans. Highl. Agric. Soc. Scotland, (5) XVI, p. 264, on 
the Norwegian ‘Tjordhest.” I cannot agree with Stejneger (Smith. Misc. 
Coll., XLVIII, p. 470; 1907) that Fitzinger (Ab. Ak. Wien, XXXI, pp. 139-212; 
1858, XXXII, pp. 391-420; 1858, XXXV, pp. 335-36; 1859) should be regarded 
as first reviser, as he mixes up both types under his E. caballus. 
Cat. Foss. Mamm. B. M., Ill, p. 89 (1886); from the Norwich Crag. 
1® Soergel, l.c.; from Steinheim a.d. Murv, Wurttemberg. 
