380 



backward extension of the nasal bones, whose expanded posterior extremities are terminated 

 by a minor or more open curve. The lateral border of the nasals which joins the premaxil- 

 lary, and the nasal processes of the premaxillary, are longer and narrower : the facial part of 

 the lacrymal is more extensive : the anterior root of the zygoma is much broader, and the 

 antero-inferior root more slender. A fracture of the outer table of the cranium shows the 

 extension of the sinuses into the parietal bones. The premolars have recently come into 



place in both jaws. 



Purchased. 



2091. A mutilated skull of a male Cape Porcupine (Hystrix cristata}. 



This specimen repeats all those characters by which No. 2090 differs from the skulls of the 

 European and N. African Porcupines. The last true molars have come into place, but their 

 summits have hardly begun to be worn. The matrix of the premolar is shown by the forma- 

 tive cavity to have acquired almost the full size of the crown, but calcification had not com- 

 menced. The teeth are removed from the left side of both upper and lower jaws, and are 

 separately displayed. The socket of the nascent premolar is shown on the right side of both 

 the upper and the lower jaws. The cavity of the cranium is exposed, showing the deep sella 

 and the posterior clinoid processes : there is not the protuberance at the fore part of the 

 petrosal which is shown in the Hystrix cristata, No. 2087. The base of the posterior pro- 

 cess of the squamosal divides the alisphenoid from the parietal, both on the inner and outer 

 sides of the skull. The frontal descends in front of this to join the alisphenoid, as well as the 

 orbitosphenoid and prefrontals. 



Purchased. 



2092. The skull of the Asiatic Porcupine (Hystrix hirsutirostris). 



The premolars have come into place in both jaws, but their summits have scarcely begun 

 to be worn. This skull equals in size that of the Cape Porcupine, but differs both from it 

 and from the European Hystrix cristata in the almost uniform breadth of the long and large 

 premaxillaries, whose broad truncated posterior extremities terminate parallel with those of 

 the nasal bones. These bones are parallelograms. The frontal bones exceed the parietals in 

 length. The temporal ridges commence anterior to the fronto-squamosal and sagittal sutures, 

 and meet to form a sharp crest above the interparietal bone, which encroaches between the 

 posterior halves of the parietals. The fissure between the squamosal and tympanic is widest 

 in the middle, instead of at its two ends ; the facial part of the lacrymal is relatively smaller 

 than in the Cape Porcupine. The bony palate is more deeply and angularly notched behind. 

 The hinder border of the lower jaw is deeper and less excavated than in the Cape or European 

 Porcupines. The enamelled part of the incisors is stained of a deep orange. The dentition, 

 being at the same stage as in the skull of the female Cape Porcupine, No. 2090, well illustrates 

 the modification of the grinding surface of the teeth characteristic of the two species. 



Hunterian. 



2093. The cranium of the Asiatic Porcupine (Hystrix hirsutirostris), in three trans- 

 verse sections. 



