PREHISTORIC TIMES IN BRITAIN. 537 



There is no doubt that the younger the pig the greater is the 

 distance separating its lacrymal's length from equality with or 

 superiority to its lacrymars height ; but the subjoined tables 

 show that there is no constant relation to be observed between 

 the growth of the entire facial skeleton out of the short propor- 

 tion of early days into the elongated muzzle of the adult, and 

 the longitudinal evolution of the lacrymal factor of that snout. 

 The longest snout, such as that of the adult Sus l/arbahis, may, 

 as Nathusius has remarked with surprise (p. 167), show a 

 lacrymal with the proportions of the domestic Sus indicus, or the 

 immature Sus scrofa, var. Jiirus ; and I venture to suggest that 

 the elongation of the lacrymal, which Professor Owen taught 

 us to call a ' mucodermal bone,' may be correlated with the evo- 

 lution of the facial warts which are found in all the Suidae with 

 such lacrymals. If these two structures are thus correlated, we 

 come to be able to explain how it is that the length of the 

 lacrymals is, though not very variable, still as variable as we have 

 found it to be ; for the facial warts themselves are a variable 

 structure, as we should from several analogies expect them to be. 

 If they were not so, it would be difficult to explain how it is that 

 in many zoological descriptions^ of our European wild boar, no 

 mention is made of the presence of warts (small ones, it is true) 

 immediately below the eyes; and inasmuch as they are so variable, 

 and probably more liable ^ to disappear in the female sex, we can, 

 on the hypothesis of the evolution of the lacrymal in length being 

 correlated with their presence, understand how the lacrymal is 

 sometimes found to be shorter than we should have expected it to 

 be in skulls such as those of the wild sows from prehistoric deposits 

 in this country, measurements of which are given p. 546. 



* De Fatio, in his • Faune des Vert^br^s de la Suisse,' 1869, p. 354, goes, if I 

 understand him rightly, further than this, by using the words * Pas de saillies 

 sur la face en dessous des yeux,' in his definition of ' Le Sanglier ordinaire, das wilde 

 Schwein.' 



2 Dr. Gray, in his description of Potamochoerus africanus (' P. Z. S.' 1868, p. 34), 

 says of the male animal's face, that it ' is swollen and often warty on the sides in front, 

 and of the females, that ' the side of the nose is simple.' Fitzinger, however, whose 

 descriptions of the external characters appear to be carefully done, does not say that 

 any such sexual difference exists in this species or in any other of the Suidae with 

 warts. There are other reasons, however, for the suggestions in the text, of which 

 the sexual limitations of the facial callosities in the orangs may be taken as an 

 example. 



