SIWALIK AND NARBADA BUNODONT SUINA. 
15—49 
mammals, except in special instances like those noticed above. From the presence 
of four incisors in some Metatlieria Prof. Albreclit comes to the further conclusion 
♦ 
that ^5 of the eutherian series really corresiDonds to iyt of the metatherian series ; 
the first reduction in number taking place by the suppression of ^ of the 
metatherian series. 
Family II.: SUIDj^. 
Extent . — For palfcontological purposes it seems best that the present family 
should be taken to include the recent family Ekotylidm.^ It is abundantly rejiresented 
in the fossil state both in the New and Old Worlds : all the species found in the 
former are, however, more or less closely related to Bicotyles ; the typical swine 
having apparently been always confined to the Old World. The Siwalik repre- 
sentatives of the family comprehend the genera Siis, Hippohyus, Sanitherium, and 
Hyotherium ; which will be treated of in this order. 
Genus I. : SUS, Linn. 
Including^ Porcula, Hodgs.; and Potamochoerus, Gray. 
Extent, dentition, etc . — The dentition of the existing species of Eus is so well 
known that it is unnecessary to describe it. It comprehends the full eutherian 
series ; but in some fossil forms the first premolar in both jaws is usually or always 
absent. In the African river-hogs {Potamochoerus) the anterior preinolar is also 
absent in both jaAvs, the talon of the last molars is smaller than in the more typical 
jDigs, and the structure of all the cheek-teeth is somewhat less complex.® In some 
of the iniocene and pliocene forms the latter features are still more pronounced, and 
it thus becomes very difficult to draw any distinction between Sus and Hyotherium, 
and impossible to draw any between Eus and Potamochoerus ; so that for palaeontological 
purposes the two living species of the latter may be included in the former. It has 
recently been showiT that the genus Porcula, Hodgs., should be merged in Eus. 
Bahirussa, besides its enormously developed canines, is readily distinguished by the 
early loss of the outer upper incisors, and the two first premolars in each jaw : the 
talons of the last molars are also smaller, and the four main columns of the molars 
more distinct than in existing species of Eus ; these teeth being, moreover, relatively 
narrower. Iti cases where only the hinder cheek-teeth of some of the more 
generalized fossil forms are known it would, hoAvever, be difficult to distinguish 
between Eus and Bahirussa. 
Recent species . — There is still a great amount of uncertainty as to the number of 
1 In vol. II. of this work fp. 146) the two families are still maintained. QQnns Heterohyus, Gerv. Zool. et Pal. 
Frang.y pi. XXXV., fig. 14), was then included in the Suida: from its resemblance to Jphelotherium it should however 
I ^ * 
very probably be referred to the Pachysimia. 
2 It is needless to allude to the numerous genera into which Siis was divided by Gray. 
3 There is, however, an almost complete transition in this respect among living pigs from 5. scro/a to Potamochwtus 
4 Garson, ‘ Proc. Zool. Soc.,’ 1883, p. 413, et. teq. 
