264 PROF. ROLLESTON GN THE DOMESTIC PIG 



that this side of the hone goes on growing from a condition of permanent inferiority in 

 Sus andamanensis till it reaches subequality or entire equality with the orbital length in 

 some Suiclse — such as Sus cristatus, Sus vittatus, Sus leucomystax, Sus taivanus, Sus 

 timoriensis, Sus papuensis, and Sus barbatus, all Suidse without facial warts — and finally 

 exceeds the orbital border in length considerably in Sus scrofa, v&r.ferus, and ordinarily 

 in Sus verrucosus (and Sus celebensis ?), and disproportionately, it may be added, in the 

 African Wart-Hog, Phacochcerus. 



There is no doubt tbat the younger tbe pig the greater is the distance separating its 

 lacrymal's length from equality with or superiority to its lacrymal's height ; but the 

 subjoined tables and the description of my figures show that there is no constant relation 

 to be observed between the growth of the entire facialskeleton out of the short proportion 

 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 barbatus, 

 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, Y&Y.ferus; 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 evolution of the facial 

 warts which are found in all the Suidss with such lacrymals. If these two structures are 

 thus correlated, Ave 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 f to disappear in the female sex, we can, on the 

 hypothesis of the evolution of the lacrymal in length being correlated with their 



the library of either the Zoological, Royal, or Linnean Society, it may nevertheless be convenient to give here the 

 results of his measurements of the borders of the lacrymal bones at different periods of the life of Sus scrofa. They 

 stand thus at p. 10 of his work of 1864 : — 



Newly born. 2 months old. 6 months old. Adult. 

 Lacrymal bone. millim. millim. millim. millim. 



Height 7 13 18 21 



Frontal border 11 20 42 60 



Malar border 3 6 25 35 



Ratio of height . 1 1:9 2-6 3 



Ratio of frontal border 1 1-8 3-8 5-5 



Ratio of malar border 1 2 8-3 11-0 



* De Fatio, in his ' Faune des Vertebres 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 ordi- 

 naire, das wilde Schwein." 



t Dr. Gray, in his description of Potamochcerus 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, docs not say that any 

 such sexual difference exists in this species or in any other of the Suida3 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. 



