LÖNNBERG, ON A NEW ORYCTEROrUS FROM NORTHERN CONGO. 13 



definite without direct comparison. Andrews says about O. 

 gaudryi (1. c. p. 296): »On the occipital surface the mastoid 

 portion of the periotic is less prominent than in the recent 

 species and is more overlapped by the squamosal» — — — 

 In O. erikssoni the mastoid portion certainly is not as pro- 

 minent on the occipital surface of the skull as in O. afer in 

 which it is distinctly convex, forming a boss, or in O. cethio- 

 picus where it lies in the same plane as the occipital. In 

 O. erikssoni the mastoid portion is on the occipital surface 

 rather deeply grooved on its proximal two thirds and then 

 slightly raised towards its lateral margin. It is not »over- 

 lapped», however, by the squamosal, although the latter, 

 especially below, projects further laterally than the mastoid 

 portion. 



With regard to the other characteristics through which 

 O. gavdryi differs from recent species O. erikssoni resembles 

 the latter. The tympanic ring, for instance, is not circular 

 as in the Pliocene animal, but oval with the long axis di- 

 rected downward and iuAvard but only slightly forward. With 

 regard to the postorbital processes O. gaudryi is most similar 

 to O. cethiojncus and least to O. erikssoni. Foramen infraor- 

 orhitale opens in O. gaudryi above the foremost molar (third 

 from behind), but so it does in several living species, although 

 in others above the second molar. In O. erikssoni the open- 

 ing is continued forward from above the foremost molar in 

 a deep groove which partly is roofed över and which extends 

 forward beyond the hindmost premolar, as may be seen on 

 the figure (fig. 2). The opening is thus practically still fur- 

 ther forward than in the fossil form. 



With regard to processus condyloideus of the mandible 

 O, erikssoni agrees with the other recent species in having a 

 longer pedicle to the condyle which is sloping and not hori- 

 zontal as in the fossil species. 



Even if O. erikssoni with regard to the teeth, and pos- 

 sibly also with regard to the structure of the occipital region 

 of the skull, shews some resemblance with the fossil species, 

 its likeness to the recent species is greater and its skull must 

 certainly be regarded as exhibiting many features of a very 

 highly developed Orycteropus as already the comparatively 

 very large size of the animal indicates that it must be. Such 

 a feature is the well developed braincase the large size of 



