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rrontals, and in the more concave lateral border of the nasal which joins the premaxillary, 

 producing a corresponding difference in the adapted border in that bone, as compared with 

 the same part in the Cape Porcupine. The cerebellar depression upon the petrosal is very 

 shallow : the fore part of the petrosal presents a large protuberance. The rhinencephalic 

 fossa is relatively of large size, and is defined by a well-marked ridge from the rest of the 

 cranial cavity. Two vascular canals are continued into its lower part from above the optic 

 foramina, instead of an open groove, as hi the Aguti. The compressed and coalesced pre- 

 frontals are shown in the left moiety of the cranium. The vomer is deeply cleft posteriorly, 

 and has coalesced with the ethmoturbinals. The anterior median part of the vomer articulates 

 with the median ascending process of the premaxillary arching over the wide vacuities which 

 lead from the nasal passages to the prepalatine apertures. In the upper jaw the last molar, 

 m 3, has been recently attained, but the deciduous molar is not shed. The alveolus of 

 reserve for its successor is exposed in the middle of the base of the socket between the three 

 diverging fangs, and is of small size ; the development of the matrix of the premolar having 

 only just commenced. The different bones are numbered on coloured labels corresponding 

 with the TABLE OF SYNONYMS. The section displays the nasal and frontal sinuses, and a 

 slight extension of the latter into the fore part of the parietal. The portion of white quill is 

 passed through the ectocarotid canal, which pierces a small part of the alisphenoid, entering 

 at its posterior margin. The alisphenoid canal, through which a portion of black quill is 

 passed, commences also at the posterior border of the alisphenoid, just above the preceding, 

 and diverges from the ectocarotid, traversing a larger proportion of the alisphenoid. The 

 ectopterygoid plate of the alisphenoid unites by suture with the pterygoid, and circumscribes 

 a large irregular vacuity called the ' interpterygoid canal.' 



Hunter ian. 



2088. The skull of a Porcupine (Hystrix cristata). 



It presents the same cranial characters as Nos. 2076 and 2087. It is from an animal which 

 had been kept in confinement, and the capsules of the matrices of the last molars and pre- 

 molars have been the seat of inflammation with tumefaction from the development of a thick 

 irregular crust of cement around the dentinal and enamel portions of the teeth. The fissure 

 between the tympanic and squamosal is wider throughout than in the Cape Porcupine. 



Presented by William Clift, Esq., F.R.S. 



2089. The left ramus of the lower jaw of an old European Porcupine {Hystrix 

 cristata), with the premolar in place and the crown worn. Hunterian. 



2090. The skull of a female Cape Porcupine (Hystrix cristata). 



Like that of the male, No. 2076, it differs from the skull of No. 2087 in the temporal ridges 

 not quite meeting above the sagittal suture, and commencing anteriorly two or three lines 

 behind the frontal suture. It also differs in the greater antero-posterior extent of the fron- 

 tals, the frontal suture being one-third longer than the sagittal suture ; it differs in the less 



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