1904.] FOREST-PIC OF CEXTRAL AFPvICA. 197 



in front of and exteiTial to tlie orbits, this being one of the 

 few chai-acters in which Hylochoirus shows more resemblance to 

 Potarnochf£rus than to Sus ; but even here it is to be noticed that 

 the spring of the zygomata has not the remarkable abraiptness 

 found in Potamochf/rus, and that Phaxochx/irus has a still more 

 prominent zygomatic boss outside and below the eye. Base of 

 skull witli two large sharpl}' defined sphenoid pits, separated from 

 each other by the high knife-like vomer, the whole sti-ucture being 

 very like the an-angement genei-ally found in PhdcochjArihs^ though 

 there is con.siderab]e variation in this respect between different 

 specimens of the latter animal. The two skulls of IIyloch(/:rus 

 also differ from each other, as the pits are more deeply hollowed 

 out and sharply defined behind in the type than in the older 

 skull. iSuch pits, present to their full extent in Phacochwnm. 

 are also found, though smaller, in BoMriijSsa, one of the most 

 primitive of pigs. There is no trace of them in Potamochf/irus 

 nor in typical Sus as represented by the Sus scrofa gi-oup ; 

 but in the peculiar Sus verracosus group there is an indication 

 of a hollowing out in the same region, and in one specimen of 

 >S'. verrucosus amhoinensis Major there is a deep pit in the 

 pterygoid on each side of the vomer — evidently a remnant of the 

 same structure. But this pit is absent in another specimen of 

 the same form. Bull* reaching up rather more than halfway 

 towards the hamular processes, thus intermediate between the 

 low bulla3 of Phacochjjiras and those of Potaniochf/irus, which 

 attain the level of the hamular processes. 



Lower jaw postei-ioi'ly about as in PrAamochKrus, not elongated 

 upwards as in Phacochfjirus, but anteriorly it is broad and spatu- 

 late as in the latter genus, in order to accommodate the widely 

 splayed caninas. 



Dentition. — The pennanent incisors, as in Phacoch(£,rus, are one 

 in number aboA'e on each side and two below, i" and i^ above and 

 i, below (all present in Sus and Potamodtvyrus) having been lost. 

 But they are larger than in the Wart-Hog, and are probably 

 never shed, as so commonly happens in old individuals of Phaco- 

 chcerus. Moreover, on one side of the single mandible available, 

 the milk-predecessor of i, is still in place, the retention of the 

 milk-tooth when the permanent one has been aborted being an 

 intermediate stage between the complete set of Siis and the 

 reduced one of Phacooh(/irus. Young examples of this latter do 

 not show any trace of a milk i.^. 



The canines present several characters of interest, and are in 

 many ways of an annectant nature. The upper ones are conical, 

 very thick and hea%y basally, indeed as much so as in PhMco- 

 chairas, but they taper more rapidly, and in the example before 

 me do not much exceed in length those of ordinary swine. The 

 reason of the comparative shortness of the upper canines of Srhs 

 is that they are so placed that the friction with the lower canines 

 cuts them obliquely across, the lines of the hinder edge of the 

 upper and front edge of the lower pair, when viewed from above, 



