12 ARKIV FÖR ZOOLOGI. BAND 3. N:0 8. 



The longitudinal diameter of the upper teeth counted 

 from behind is resp. 10; 12,5; 11, .5; 9,3 (8,.5); 4,5 (4); 6 (?) 

 mm. Their greatest transversal diameter is in the same order 

 resp. 8; 9; 7,5; 5; 3,5 (1,5); 2,.s mm. 



In the lower jaw the longitudinal diameter of the teeth 

 counted from behind is resp. 10,5; 13; 11,5; 8; 6; 5,3 mm. 

 Their transversal thickness is resp. 8; 9; 7; 5; 3,5; 3 mm. 



These dimensions are larger than in the specimens of O. 

 af er and O. cethiopicus I have had for comparison. The hindmost 

 molar is not only larger than in other species, but its shape is 

 different from t hat in other recent species. Its diameter is namely 

 longer (that is, the tooth is less cylindrical) and it is more dis- 

 tinctly divided in two lobes like the two anterior molars. while 

 the same tooth usually in other living species is almost cylin- 

 drical, and, if it is oval in section, the grooves dividing the 

 anterior and posterior lobes are shallow and only little pro- 

 nounced. In O. erikssoni this semidivision of the hindmost 

 molar is conspicuous in the upper (fig. 4) as well as in the 

 lower jaw and both on inner and outer side of the tooth. 

 It is, however, somewhat less pronounced than in the fossil 

 O gaudryi from Samos according to Andre w,s' figure in Proc. 

 Zool. Soc. 1886 (p. 297). Nevertheless this semidivision of 

 the hindmost molar in O. erikssoni is a primitive characteri- 

 stic retained, although the primitiveness consists therein that 

 the reduction has not gone so far as in other recent mem- 

 bers of the genus ^ 



Another possible feature of resemblance between the 

 fossil species and O. erikssoni may be found on the occipital 

 surface of the skull, although it is difficult to say anything 



^ About another perliaps primitive chai-acteinstic there appearf? to be 

 some doubt, that is about questionable alveoles for canines. At the suture 

 between the maxillary and the prsemaxillary just in the place where can- 

 ines normally have their situation there is in O. erikssoni on either side a 

 deep liole vvhich has the shape of a narrow alveole and it might be the 

 rudiment of such a one. Forsyth Major (Proc. Zool. Soc. 1893 p. 239 — 

 40) found eight teeth on either side in the mandible of the fossil Orycte- 

 ropus from »the Upper Miocone of Maiagha (Persia)» and regards the fore- 

 niost as a canine. The snout of the specimen was broken but he believes 

 that there has been a canine as well. This is, however, only a supposition. 

 The presence of more than 7 teeth on either side of the upper jaw will 

 be fvirther discussed at the end of this paper. 



At the end of the mandible of O. erikssoni as well as of that of 

 other species there is a long groove often conspicuously divided in a series 

 ot pits looking like small alveoles, the two (sometimes even three) fore- 

 most of which are especially plainly visible. Are these the last traces of 

 former incisors? 



