1894.] ANATOMY OF ATHERURA AFRICAN A. 677 



In A. africana the suture between the malar bone and the 

 maxilla is much further forward than in A. macnira, its distance 

 from the nearest point of the great iufraorbital foramen being 

 from g to j in., while in A. macrura it is considerably over | in. 



Another point worthy of notice is that in 4 out of 6 skulls of 

 A. africana an os antiepilepticum or Wormian bone at the junction 

 of the coronal and sagittal sutures was present. In four skulls 

 of A. macrura it was not seen once 1 , 



The cervical vertebrae are remarkable for the large and recurved 

 spine of the atlas. The sixth shows a large ventral tubercle on 

 the transverse process corresponding to the carotid tubercle of 

 human anatomy. In the seventh this tubercle is suppressed. 



The thoracic vertebrae are 14 in number, the anticlinal being the 

 13th. The transverse processes gradually broaden and tend to 

 bifurcate until at the 8th there is a fairly distinct metapophysis 

 projecting from the anterior part and an anapophysis from the 

 posterior. 



The lumbar vertebrae (fig. 2, p. 678) are 5. The anapophyses are 

 well marked until the last one, where they disappear 2 . Ventral to 

 the dise between the first and second vertebrae are two ossific nodules 

 about the size of pins' heads, which apparently are serially homo- 

 logous with the chevron-bones in the caudal region, and probably 

 correspond to the intercentral in the Mole, although 1 believe 

 that these structures have not yet been described in Rodents. In 

 another specimen which I examined I found these nodules between 

 the 2nd and 3rd, 3rd and 4th, and 5th and 1st sacral 3 . 



The sacral vertebrae are sometimes three, sometimes four. All 

 the costal processes are completely fused into a horizontal plate, 

 while the spines are only slightly fused. In the structure of the 

 sacrum Atherura agrees with Hystrioe and differs considerably from 

 the Tree-Porcupines. 



There are 24 caudal vertebrae, the first four of which have 

 projections from the ventral surfaces of the costal processes. 

 Between the last sacral and first caudal vertebrae chevron-bones 

 are seen as small nodules. Between the first and second caudals 

 there is a small haemal arch ending ventrally in a point ; beyond 

 this the haemal spines broaden out anteriorly but are compressed 

 laterally ; there are altogether 16 of them. 



The sternum consists in one case of five and in another of six 

 sternebrae. In front of the anterior one there is a leaf-shaped 

 cartilage. The anterior sternebra or manubrium is remarkable in 

 the animal I dissected in that the first and second costal cartilages 



1 W. Gruber in 'M6moires cle l'Academie de St. Petersbourg,' xix. no. 9, 

 describes the presence of this bone in several Rodents, but not in Porcupines. 



2 In another specimen they were absent in the last two. 



3 The occurrence of these paired intercentra is interesting when compared 

 with a paper by Boulenger, P. Z. S. 1891, pp. 114 & 170. In it he points out 

 that, in Lizards, the intercentra or hypapophyses may be either paired or 

 median. 



