452 DR. R. BROOM ON THE 



Cynoclonts we may infer that the early mammals still retained 

 it, and possibly Chrysochloris and its ancestors have never lost 

 this ancestral character which all other known mammals have 

 lost. 



The occiput of Chrysochloris is very interesting when compared 

 with its supposed ally Hemicentetes (text-fig. 1, B). It Avill be 

 observed that the most striking diffei-ence is the entire absence 

 of even a rudimentary tabular, whose place is occupied by lateral 

 extensions of the supraoccipital and parietal. There are also 

 consider-able differences in the relative sizes of the other 

 elements. 



Memhrane-hones of the base of the skull of the neioly-horn 

 Chrysochloris hottentota. 



The skull of the newly-born Chrysochloris hottentota is now 

 represented by 710 transverse sections. From sections 1 to 316 

 the series is complete and continuous. Here, unfortunately, the 

 block of paraffin has been placed in the microtome in the reversed 

 position and a wedge-shaped section of considerable thickness has 

 been removed. Between sections 372 and 373 about eight sec- 

 tions are missing. Though these imperfections have increased 

 the difficulty of reconstruction, they have fortunately not resulted 

 in the loss of any fact of importance. In the reconstructions I 

 have made, the gaps have been restored, as can be done with 

 complete confidence, and the slight obliquity of the posterior half 

 of the skull corrected. 



As there is nothing of importance to be seen on the upper side 

 of the skull that is not better seen in the slightly older dissected 

 skull, I shall confine my description to the interesting condition 

 of the base. 



The whole palate is relatively shorter and broader than in the 

 older stage. The premaxilla is already well ossified, and has two 

 large open sockets for the 1st and 2nd developing milk-incisors. 

 The cavity for the third developing tooth is only partly formed 

 by the premaxilla, and partly by the maxilla. There seems little 

 doubt, however, that this 3rd tooth is also, as has been generally 

 held, an incisor. The palatine process is rather short, and there 

 is a fairly large anterior palatine foramen. 



The maxillary bone has a very broad but rather short palatal 

 plate. There are distinct concavities for part of the 3rd milk- 

 incisor, the milk- canine, the thi'ee milk-premolars, and for the 

 1st true molar. The dental lamina which is going to form the 

 2nd and 3rd molars is not at this stage supported by bone. 

 From the lamina of bone which forms the outer protection for 

 the dental germs, there is continued backwards the process of 

 bone which forms the zygomatic arch. There is no distinct 

 jugal. 



The palatine is seen as a fairly large bone behind the 

 maxillary. The plates forming the secondary palate are well 



