1352 



CLASS MAMMALIA. 



B. gawus now living in the same regions. In the Taurine group 

 the frontals (fig. 1223) are extremely elongated, and the horn-cores, 

 which in the type species are rounded, are placed immediately over 

 the occiput. To this group may be referred B. planifrons and B. 

 acutifrons of the Pliocene of the Siwalik Hills ; the latter being re- 

 markable for its sharply angulated frontals and its enormous horn- 

 cores, which have a pyriform section. Another member is B. nama- 

 dicus of the Pleistocene of Central India, which presents some ap- 

 proximation to the Bibovine group ; but the best known fossil Ox is 

 the Urus of the European Pleistocene (fig. 1223), which appears to 

 be only a larger form of the existing Ox {Bos taurus), and of which 

 the descendants of wild races are still preserved in Chillingham and 

 some other British parks. A still smaller race, whose remains have 

 been found in the turbaries and fens of England, and have been 

 described under the names of B. lo?igifrons and B. frontosus, 

 seems to be only a stunted variety of the same species, from which it 

 is probable that the small cattle of Wales and Scotland have been 

 derived. 



Suborder 2. — Perissodactyla. — The characters possessed by 

 this suborder in common with the Artiodactyla are noticed under 

 that head. The distinctive features of the Perissodactyla are to be 

 found in the truncated distal surface of the astragalus (fig. 1224); 



the circumstance that the third digit 

 in both the fore and hind feet is sym- 

 metrical in itself, and larger than 

 either of the others (fig. 1225); the 

 presence (except in Chalicotheriutri) 

 of a third trochanter to the femur 

 (fig. 1226); and the non-articulation 

 of the fibula with the calcaneum. 

 Other characters very generally ob- 

 servable in this suborder are, that the 

 whole of the series of cheek-teeth are 

 in contact with one another ; that the 

 upper premolars are nearly or quite 

 as complex as the true molars ; that 

 the last lower true molar frequently has no third lobe, and that 

 when such third lobe is present, it is absent in the last lower milk- 

 molar ; while the first tooth of the cheek series is sometimes pre- 

 ceded by a milk-tooth. In all existing forms the number of the 

 dorso-lumbar vertebras is never less than twenty-two, and is usually 

 twenty-three ; while the nasals are expanded posteriorly. The 

 stomach is simple, and the placenta diffused. In existing forms 

 the cervical vertebras are markedly opisthoccelous. The upper true 

 molars are constructed on some modification of what is known as 



Fig. 1224. — Anterior view of the left 

 astragalus of the Horse (Equus cabal- 

 lus). One-half natural size. 



