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JOURNAL OF MAMMALOGY 
Wayland^^ as Equus zeylanicus and in Equus leptostylus Matsumoto^® 
from Honan j China. Lydekker has made a strong case of the presence 
in E. sivalensis, E, stenonis and the Arab of a preorbital depression; 
but since the same character is found in the southern but not in the 
northern local races of E. quagga, 1 cannot regard it as of specific value. 
It has frequently been maintained that the horses of the second 
(caballus-rohustus) type were derived from those of the stenonis group, 
chiefly on the assumption (1) that stenonis is older (Pliocene) (2) that 
in some of the older specimens of ‘^robustus” only a rather small proto- 
cone is found in the cheekteeth. This is disproved however by a tooth 
from the Red Crag of Bawdsey, Suffolk/^ contemporaneous with or 
even older than stenonis and distinguishable, except in size, from the 
most recent teeth of E. caballus only in details discussed below, I 
am not quite satisfied whether the remains usually referred to E, 
stenonis and robustus respectively from the Oreston Cave near Ply- 
mouth, from Rentes Hole near Torquay, from the lower deposits at 
Mosbach near Wiesbaden, and from the older Auvergne strata are 
all found in the same horizon, but this is of little importance since 
the Bawdsey tooth^® is older than either of them. There is no doubt, 
therefore, that both species occurred together in Europe during upper 
Pliocene and probably also basal Pleistocene times. 
I shall now designate the first of these types as Equus stenonis. 
The names atlanticus, ligeris, mauretanicus, persicus^^ and stenonis 
decidedly belong to this species and may be races of it; their exact 
value and relation among each other I am not at present prepared 
to state. Remains of Pliocene age have been found at Maragha in 
northern Persia, in the Val d’Arno, Italy, at various localities in France, 
southern Germany, Austria-Hungary, and southern England; some, 
as those of Mosbach or the Norfolk Forest Beds as well as some of 
the British caverns, are early Pleistocene; the most recent materials 
appear to be those from northern Africa which have been described 
12 Spolia Zeylan., X, pp. 261-280 (1916); the tooth of E. caballus figured for 
comparison obviously belongs to an Indian domestic horse and is of the Arab 
or stenonis type. 
1^ Science Reports of the Tohoku Imperial University, Sendai, 2nd ser. (Ge- 
ology), III, no. 1, pp. 29-30 (not seen in the original; figure copied by Wayland). 
14 Owen, Quart. Journ. Geol. Soc., XII, p. 223, fig. 12 (p. 233) (1856). 
1® The exact age of these strata is probably upper Pliocene. 
i®Wilckens, Anz. Ak. Wien, XXIV, p. 43 (1887), and Nov. Act. Leop., LII, 
p. 268, pis. XI, figs. 18, 19, X, figs. 21-24, XIII, figs. 43-46, XIV, figs. 47 (1887); 
from the lower or middle Pliocene of Maragha, Persia. 
