74 



DOMESTIC PIGS. 



Chap. III. 



or 



length may be due either to descent from a distinct species 

 to more ancient domestication. The number of mammas vary, 

 as does the period of gestation. The latest authority says 2 ' 

 that "the period averages from 17 to 20 weeks," but I think 

 there must be some error in this statement: in M. Tessier's 

 observations on 25 sows it varied from 109 to 123 days. The 

 Kev. W. D.Fox has given me ten carefully recorded cases 

 with well-bred pigs, in which the period varied from 101 to 116 

 days. According to Nathusius the period is shortest in the races 

 which come early to maturity ; but in these latter the course 

 of development does not appear to be actually shortened, for 

 the young animal is born, judging from the state of the skull, 

 less fully developed, or in a more embryonic condition, 22 than 

 in the case of common swine, which arrive at maturitv at a 

 later age. In the highly cultivated and early matured races 

 the teeth, also, are developed earlier. 



The difference in the number of the vertebrae and ribs in 

 different kinds of pigs, as observed by Mr. Eyton, 23 and as given 

 in the following table, has often been quoted. The African 

 sow probably belongs to the 8. scrofa type; and Mr. Eyton 

 informs me that, since the publication of his paper, cross-bred 

 animals from the African and English races were found by Lord 

 Hill to be perfectly fertile. 





English 



Long-legged 



Male. 



African 

 Female. 



Chinese 



Male. 



Wild Boar, 

 from Cuvier. 



French 

 Domestic 

 Boar, from 



Cuvier. 



Dorsal vertebrae . . 



Dorsal and lumbar \ 

 together . . . . J 



Sacral 



15 

 6 



13 



6 



15 14 

 4 5 



14 

 5 



21 



5 



19 



5 



19 

 4 



19 

 4 



19 

 4 



Total number ofl 

 vertebrse . . . . / 



26 



24 



23 



23 



23 



21 S. Sidney, 'The Pig,' p. 61. 



22 ' Schweinesch'adel,' s. 2, 20. 



23 « Proc. Zoolog. Soc.,' 1837, p. 23. 

 I have not given the caudal vertebrse, 

 as Mr. Eyton says some might possibly 

 have been lost. I have added together 

 the dorsal and lumbar vertebrae, owing 



to Prof. Owen's remarks (' Journal Linn. 

 Soc.,' vol. ii. p. 28) on the difference 

 between dorsal and lumbar vertebrse 

 depending only on the development of 

 the ribs. Nevertheless the difference in 

 the number of the ribs in pigs deserves 

 notice. 



