262 PROF. ROLLESTON ON THE DOMESTIC PIG 



had occasion, in going over the extensive series of skulls of Indian Wild Hogs which 

 have been available to me, to note an almost, I have never noted an entirely complete 

 disappearance of it. The fronto-lacrymal ridge is not, even in the aged hog, a mere 

 expansion or dilatation of the frontal bone : it is underlain, it is true, by an arm of the 

 frontal sinuses ; but it has thick and independent walls of its own. Though not quite 

 exactly homologous with the supraciliary ridges of human anatomy, it is nevertheless 

 very closely comparable with them. In some varieties of the human species the supra- 

 ciliary ridges, whether underlain by sinuses or not, are very constantly developed into great 

 prominences. In a classification, indeed, of human crania proposed by Dr. Williamson *, 

 " skulls with the supraciliary ridge so prominent as to overshadow the face" formed one out 

 of four classes into which all crania were divided. It is not necessary to go so far as this 

 for acknowledging that this character may become, in the Suidse at least, a race character f. 



The second in order of the three points which, taken together, as they usually exist 

 together, with the fourth, that relating to the lacrymal, help us to identify Sus cristatus, is 

 complexity of its third molar, at least in male specimens, and specially the complexity of 

 that part of the tooth which lies posteriorly to the two primary bicuspidate lobes. 



A reference to my description of fig. 8 (where the third lower-jaw molar of Sus 

 andamanensis represents this often complex tooth reduced to great simplicity) will enable 

 the reader to understand this second point of distinction between Sus cristatus and Sus 

 scrofa more readily than any verbal description, however long, without such reference. 

 It may be sufficient to say here that the division of the third molar which lies posteriorly 

 to the two anterior lobes, is, in the male Sus cristatus, equal sometimes in size to and 

 sometimes even greater than both those other lobes taken together. This is not often, 

 though it is occasionally, the case in Sus scrofa, var. ferus, of modern times. Nor is it 

 the case in the females of Sus cristatus ; so that the greater development observed in the 

 males may perhaps be due to the working of the law of sexual battle. The large size of 

 the canines postulates a large determination of blood to the jaw ; and the large size of the 

 third molar, a tooth evolved at the period of sexual maturity, when the animal " venerem 

 et prselia tentat," may be, to use a word suggested long ago by myself J, " tautogeneous " 

 with it. Still the fact that the third molars are small both in Sua barbatm and Sus bar- 

 birussa shows that this smallness cannot always be explained on physiological grounds. 



The third point, that of the straightness of the naso-frontal suture, appears to have 

 some classificatory value, whether we look at it with the light furnished by its 

 importance and validity in the classification or identification of other animals, or in that 

 furnished by the facts of its own developmental history. 



The nasal and the frontal bones together form a roof over the ethmoid and the turbinal 

 bones ; and as there is no apparent physiological reason why they should contribute in 



* Observations on Human Crania in Museum, Fort Pitt, Chatham, 1857- 



t It is observable in the pigmy Nepal pig, Porcula salvlania, as also in the African Potamochm-us. It does not 

 appear to me that male Suicta possess it more markedly than females ; and herein it differs from the supraciliary- 

 ridge development as seen in our own species, as also from the race-mark to be next mentioned. An analogous 

 eminence, rudimentary in S. papuensis, occupies the middle frontal line over an area homologous with the human 

 glabella in each of four pig's skulls brought from the Admiralty Islands by H.M.S. < Challenger.' 



t Nat. Hist. Rev. Oct. 1861, p. 486. 



