Nat. Gen.' tome 3 page 441.), their length to that of the body in the wild boar is as 9 to 1,--in the common domestic boar as 13.5 to 1,--and in the Siam breed as 16 to 1. In this latter breed the greater length may be due either to descent from a distinct species or to more ancient domestication. The number of mammae vary, as does the period of gestation. The latest authority says (3/21. S. Sidney 'The Pig' page 61.) 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 Rev. 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 the course of their 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 (3/22. 'Schweineschadel' s. 2, 20.) than in the case of common swine. 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 (3/23. 'Proc. Zoolog. Soc.' 1837 page 23. I have not given the caudal vertebrae, 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.' volume 2 page 28) on the difference between dorsal and lumbar vertebrae depending only on the development of the ribs. Nevertheless the difference in the number of the ribs in pigs deserves notice. M. Sanson gives the number of lumbar vertebrae in various pigs; 'Comptes Rendus' 93 page 843.), and as given in the following table, has often been quoted. The African sow probably belongs to the S. scrofa type; and Mr. Eyton informs me that, since the publication of this paper, cross-bred animals from the African and English races were found by Lord Hill to be perfectly fertile.
TABLE 2: NUMBER OF VERTEBRAE IN VARIOUS PIGS:
ENGLISH LONG-LEGGED MALE.
Dorsal 15. Lumbar 6. Dorsal plus Lumbar 21. Sacral 5. Total 26.
AFRICAN FEMALE.
Dorsal 13. Lumbar 6. Dorsal plus Lumbar 19. Sacral 5. Total 24.
CHINESE MALE.
Dorsal 15. Lumbar 4. Dorsal plus Lumbar 19. Sacral 4. Total 23.
WILD BOAR FROM CUVIER.
Dorsal 14. Lumbar 5. Dorsal plus Lumbar 19. Sacral 4. Total 23.
FRENCH DOMESTIC BOAR, FROM CUVIER.
Dorsal 14. Lumbar 5. Dorsal plus Lumbar 19. Sacral 4. Total 23.
Some semi-monstrous breeds deserve notice. From the time of Aristotle to the present time solid-hoofed swine have occasionally been observed in various parts of the world. Although this peculiarity is strongly inherited, it is hardly probable that all the animals with solid hoofs have descended from the same parents; it is more probable that the same peculiarity has reappeared at various times and places. Dr. Struthers has lately described and figured (3/24. 'Edinburgh New Philosoph. Journal' April 1863. See also De Blainville 'Osteographie' page 128 for various authorities on this subject.) the structure of the feet; in both front and hind feet the distal phalanges of the two greater toes are represented by a single, great, hoof-bearing phalanx; and in the front feet, the middle phalanges are represented by a bone which is single towards the lower end, but bears two separate articulations towards the upper end. From other accounts it appears that an intermediate toe is likewise sometimes superadded.
(FIGURE 4. OLD IRISH PIG, with jaw appendages. (Copied from H.D. Richardson on Pigs.))
Another curious anomaly is offered by the appendages, described by M. Eudes-Deslongchamps as often characterizing the Normandy pigs. These appendages are always attached to the same spot, to the corners of the jaw; they are cylindrical, about three inches in length, covered with bristles, and with a pencil of bristles rising out of a sinus on one side: they have a cartilaginous centre, with two small longitudinal muscles they occur either symmetrically on both sides of the face or on one side alone. Richardson figures them on the gaunt old "Irish Greyhound pig;" and Nathusius states that they occasionally appear in all the long eared races, but are not strictly inherited, for they occur or fail in animals of the same litter.