The shoulder-stripe on the ass is sometimes double, and Mr. Blyth has seen even three or four parallel stripes.[143] I have observed in ten cases shoulder-stripes abruptly truncated at the lower end, with the anterior angle produced into a tapering point, precisely as has been figured in the dun Devonshire pony. I have seen three cases of the terminal portion abruptly and angularly bent; and two cases of a distinct though slight forking. In Syria, Dr. Hooker and his party observed for me no less than five instances of the shoulder-stripe being plainly forked over the fore leg. In the common mule it is likewise sometimes forked. When I first noticed the forking and angular bending of the shoulder-stripe, I had seen enough of the stripes {64} in the various equine species to feel convinced that even a character so unimportant as this had a distinct meaning, and was thus led to attend to the subject. I now find that in the _Asinus Burchellii_ and _quagga_, the stripe which corresponds with the shoulder-stripe of the ass, as well as some of the stripes on the neck, bifurcate, and that some of those near the shoulder have their extremities angularly bent backwards. The forking and angular bending of the stripes on the shoulders apparently stand in relation with the changed direction of the nearly upright stripes on the sides of the body and neck to the transverse bars on the legs. Finally we see that the presence of shoulder, leg, and spinal stripes in the horse,--their occasional absence in the ass,--the occurrence of double and triple shoulder-stripes in both animals, and the similar manner in which these stripes terminate at their lower extremities,--are all cases of analogous variation in the horse and ass. These cases are probably not due to similar conditions acting on similar constitutions, but to a partial reversion in colour to the common progenitor of these two species, as well as of the other species of the genus. We shall hereafter have to return to this subject, and discuss it more fully. * * * * * {65} CHAPTER III. PIGS--CATTLE--SHEEP--GOATS. PIGS BELONG TO TWO DISTINCT TYPES, SUS SCROFA AND INDICA--TORF-SCHWEIN--JAPAN PIG--FERTILITY OF CROSSED PIGS--CHANGES IN THE SKULL OF THE HIGHLY CULTIVATED RACES--CONVERGENCE OF CHARACTER--GESTATION--SOLID-HOOFED SWINE--CURIOUS APPENDAGES TO THE JAWS--DECREASE IN SIZE OF THE TUSKS--YOUNG PIGS LONGITUDINALLY STRIPED--FERAL PIGS--CROSSED BREEDS. CATTLE.--ZEBU A DISTINCT SPECIES--EUROPEAN CATTLE PROBABLY DESCENDED FROM THREE WILD FORMS--ALL THE RACES NOW FERTILE TOGETHER--BRITISH PARK CATTLE--ON THE COLOUR OF THE ABORIGINAL SPECIES--CONSTITUTIONAL DIFFERENCES--SOUTH AFRICAN RACES--SOUTH AMERICAN RACES--NIATA CATTLE--ORIGIN OF THE VARIOUS RACES OF CATTLE.