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Genus III. LIMNOTRAGUS (nom. nov.). 
Type. 
Hydrotragus, Gray, Cat. Rum. B. M. p. 49 (1872) (nec Fitz.)*. . . . IL. spexu. 
Medium or large-sized Antelopes allied to Tragelaphus, but with rougher 
and shaggier coats, longer legs, and with horns which more nearly approach 
those of Strepsiceros, as they show a strong tendency to assume a third twist. 
Further, Zimnotragus differs strikingly from Tragelaphus and Strepsiceros in 
the structure of its feet, the hoofs being often nearly three times as long 
(measured along the front edge) as thick (measured along the margin of the 
pastern). Moreover, the skin which covers the back of the pastern is 
denuded of hair, and thick and horny, being practically of the same consistency 
as the upper rim of the posterior side of the hoof. 
It is not without some hesitation that we refer to a separate genus those 
species of Tragelaphine Antelopes (hitherto placed in Tragelaphus) which have 
undergone certain special modifications of structure in adaptation to a semi- 
aquatic mode of life. In the species of Tragelaphus discussed in the preceding 
part of this work, as well as in all the other genera of Tragelaphine, the feet 
adhere to the digitigrade type characteristic of most of the ruminant artiodactyle 
Ungulates, retaining the short narrow hoofs and strong elastic ankles fitted 
for easy and swift progress over the firm soil of the veldt or woodland. In the 
species of Limnotragus, on the contrary, the feet are furnished with hoofs of 
relatively enormous length, which spread far apart at every step, and are 
obviously designed to enable their owner to pass over the soft soil of marshes 
and river-banks without sinking deeply into the ground. This modification 
is accompanied by an increase in the flexibility of the ankle-joints, which are 
capable of yielding to the weight of the body, so as to allow the false-hoofs 
and the smooth tough horny skin at the back of the pasterns to rest upon 
the soil, and thus to further augment the supporting area of the foot. It is 
these peculiarities in the structure of the feet, in conjunction with a length of 
limb exceeding that of other Tragelaphines, which impart to the species 
of Limnotragus that characteristic semiplantigrade aspect and that unusual 
* Vide Sitz. Ak. Wien, Bd. lix. p. 175 (1869). 
VOL. IV. x 
