The Madagascar Piguiy Hippopotamus. 



195 



and H. pnlceindiciis on one side and H. ampMbius on the other ; the 

 lower end of the whole line being occupied by the most generalized 

 form, H. Liheriensis of West Africa, the top by the most specialized, 

 H. major of the Upper Pliocene of Europe. 



The affinities thus expressed are based chiefly on the relative 

 pi'oportions of the cranial and facial parts of the skull, the former 

 being greatly developed in H. Liheriensis, whereas in H. amphibius 

 and in the H. major of the Upper Pliocene the cranial portion is much 

 reduced, the facial portion on the contrary is enormously produced. 

 The various crania from Madagascar have, in this respect, much 

 resemblance to H. Sivalensis, the cranial portion, however, being 

 somewhat shorter, the facial portion somewhat more elongate ; so 

 that the orbit occupies a less central position than in H. Sivalensis 

 and, as a matter of course, still less so than in H. Liheriensis. " The 

 Malagasy forms thus constitute a step farther in the direction of 

 S. amphibius, the breadth of the intraorbital region being much 

 less than in the African species and the same as in JB". Sivalensis." ^ 



Fig. 2. 



—Hippopotamus Madagasccirletisis, Guldb. Frontal region of a skull from 

 Sirabe, in the British Museum (Natural History). 



/. frontal; I. lacrymal ; m. malar ; mx. maxillary; n. nasal bone. 



These changes are reflected by the position of the lacrymal. In 

 B.. Liheriensis and H. Sivalensis (Text-fig. 1) the lacrymal is entirely 

 separated from the nasal by the anterior prolongation of the frontal, 

 which thus comes into contact with the maxillary ; whereas in 

 H. amphibius the lacrymal is usually broadly interposed between 

 the frontal and maxillary.^ I found long ago that the skulls from 

 Sirabe exhibit in this respect also an intermediate position. As 

 a rule, the lacrymal departs from the orbital margin in an inward 

 direction and reaches the nasal, with which it broadly unites, thus 

 shutting out the frontal from a connection with the maxillary. 



1 Op. cit., p. 977. 



2 See the exceptions in my paper, loc. cit., pp. 977, 978 ; and in Stehlin, Abhandl. 

 Schweiz. Palaeont. Ges., vol. xxyii (1900), p. 434, footnote. 



