142 EINAR LÖNNBERG, MAMMALS COLLECTED BY THE SWEDISH ZOOLOGICAL EXPEDITION ETC. 
terial. It could be expected that the Wart-hogs of these plains should belong to 
Phacocherus massaicus LÖNNBERG this is, however, not the case. I had the oppor- 
tunity of measuring the skull of an adult boar which had been sent to Mr. KLEIN 
four mounting. 'The upper mesial length of this skull from the tip of the nasals to 
the occipital ridge was about 427 mm.; the interorbital breadth 127 mm.; the width 
of the parietal flat area 43 mm.; and the distance from the occipital crest to a trans- 
versal line through the middle of the orbits 75 mm. These measurements prove 
that the difference from Ph. massaicus is very considerable. The postorbital region 
is rather long in both, viz. 14 ”/o of the length of the head in Ph. massaicus,' and 15 ”/o 
in the Nairobi skull, but the posterior region of the skull is much narrower in the 
latter. This is proved by the fact that the interorbital breadth is only 29 ?/o of the 
length of the skull, against 38,8 ”/o in Ph. massaicus, and the width of the parietal 
flat area is only 10 ”/o against 14,5 ”/o in Ph. massaicus. In this respect the Nairobi 
Warthog is intermediate between Ph. massaicus and Ph. africanus celiani in which 
latter the interorbital breadth is 31,7 ”/o, and the width of the parietal flat area is 
6,3 ”/o. This intermediate stage of the Nairobi Warthog appear to indicate its racial 
distinetness, but for lack of material I cannot express any definite opinion. ; 
During my stay near HEscarpment station in the beginning of January 1911 
I bought a quite young pig of Wart-hog from the Kedong valley which a Kikuyu 
brought to my camp. 
Hippopotamideae. 
Hippopotamus amphibius LIN. 
Below Chanler Falls the river Guaso Nyiri was inhabited” by Hippopotamuses. 
Spoors were seen now and then on the sand-banks in the river and also on dry land, 
but the animals were not very numerous in that portion of the river along which I 
passed. This appears to be quite natural because the river is during the dry season 
in most places so shallow that the water would not cover a fullgrown Hippopotamus, 
and in addition to this, there is hardly any vegetation on which such animals could 
feed. At two occasions, however, I had a very good opportunity of watching such 
animals. The first time this happened, a »Kiboko» had passed close to the camp 
just before sunrise. I got information about this and hurried after it. Some little 
distance above the camp it entered the river again, and when the sun had risen it 
was found to have taken its refuge to a place where the river was running rather 
swiftly and with strong current through a narrow caion, where the water accordingly 
was deep. I sat watching it on a rock opposite, and it lifted its snout regularly to 
breathe. When I saw that it was an immature specimen 1 did not want to shoot 
it as it would have been »wanton destruction», and too much of that kind is to be 
! Conf. LÖNNBERG: Proc. Zool. Soc. London 1908 p. 937. 
>” Once or twice spoors were also seen above these falls. 
