1866.] DR. J. E. GRAY ON THE SPECIES OF PORCUPINES. 309 



South Africa {Peters; B.M., skin); Southern Europe, Portugal 

 (B.M., stuffed skin and skull). 



I am not aware of any external characters by which this species 

 can be distinguished from the Hystrix cristata, though the skull 

 is so different ; indeed I am daily more convinced that there are 

 three classes of species. The most numerous class consists of those 

 which can be distinguished by their external and their osteological 

 characters ; others can only be distinguished by their osteological 

 characters, the outer appearance being common to two or more species ; 

 and, thirdly, there are species which are very different externally, but 

 which have skeletons that are so similar that they would not be di- 

 stinguishable except for the external differences,— that is, speaking 

 of the adult animal. But there are also species, as I have shown this 

 evening respecting the South-American Tortoises, which are only to 

 be distinguished when the animals are studied in all their ages— for 

 example, which are to be distinguished in their young, but not in 

 their adult age, or vice versa. 



M. de Blainville regards all the Crested Porcupines as a single 

 species ; for he represents the skulls with the wide and the narrow in- 

 termaxillaries all under the name of H. cristata of Algeria, Caffraria, 

 Senegal, Syria, Europe, and Bengal, the Bengal and Syrian skull 

 being Hystrices, and the others Acanthia, or rather (Edocephali. 



If the figures are accurate copies of the skulls, the hinder part of 

 the intermaxillaries in the specimen figured from Senegal is wider 

 than in that from Caffraria; but the skull from Algeria seems to be 

 intermediate in form between the other two. 



Dr. Peters, in his description of his H. africa australis, in the 

 'Reise nach Mossambique,' p. 1/0, published in 1852, entirely over- 

 looks the fact that the skull figured by Schreber, Cuvier, and several 

 other authors is exactly similar to the one he figures, and to which 

 he gives a new name — overlooking also my paper in the ' Proc. Zool. 

 Soc.' for 1847, where the distinctions are pointed out. 



Dr. Sclater, when describing the Orange-spined Porcupine (H. ma- 

 labarica) in the ' Proc. Zool. Soc' I860, p. 356, gives a list of four 

 species of Crested Porcupines. He separates H . malabarica from H. 

 leucura of Sykes, and in the synonymy of the latter species has most 

 erroneously included the Hystrix cristata of my Monograph, which 

 is found in Europe and North Africa and is very distinct externally 

 (by the length and form of the spines) from the Indian species. On 

 the other hand, he has separated the Acanthion cuvieri of my Mono- 

 graph (from Europe and Africa) as distinct from the H. africcd aus- 

 tralis of Peters, from South Africa, which I do not think he would 

 have done if he had examined and compared carefully the skulls and 

 stuffed specimens of the animals in the British Museum Collection. 



2. AcANTHOCHOSRUS. 



The nape with a short, thin, compressed crest, formed of a few 

 short spines. The skull elongate ; crown slightly arched. The nasal 

 bones broad, truncated behind, reaching to the front of the orbit. 

 The spines of the front part of the body flat, subtriangular, grooved. 

 The dorsal spines cylindrical, white, with a single central black ring. 



