432 



The anatomical differences of 6 species, the possible ancestors 

 of the domestic horse, are briefly described. Three of these species, 

 which have been found in the Pliocene deposits, are Equus siva- 

 lensis, the oldest true horse known to science, found in the Siwalik 

 deposits of northern India, E. stenonis of Europe and Northern Africa 

 and E. gracilis (Asinus fossilis of Owen), also found in Europe and 

 Africa. The three principal Pleistocene types are E. nomadicus, 

 E. fossilis, and E. robustus. Some relationships between these species 

 and the modern breeds are briefly noted. 



I. B. WOOD. The Inheritance of Horns and Face colour in 

 Sheep. The Journal of Agricultural Science ', vol. Ill, part II, 

 Pp. 145-155, October 1909. 



This article setting forth the results whith have been obtained 

 up to the present by the experiments on the inheritance of horns 

 and face colour in sheep (described in a preliminary note published 

 four years ago in the Journal of Agricultural Science, vol. I, p. 364) 

 is not a final pronouncement and indicates the kind of difficulties 

 which anyone who proposes to work on Mendelian lines with large 

 animals must be prepared to face. 



The parental types which were used in the crossing, were the 

 Dorset Horn and the Suffolk. The Dorset Horn breed has a pure 

 white face and legs. Both sexes have large horns, those of the 

 male being larger and more spiral than those of the female. The 

 Suffolk breed has a pure black face, its head is quite bare of wool, 

 and both sexes are normally free from horns. 



The experiment was begun in the autumn of 1903 by crossing 

 a Dorset Horn ram with 30 Suffolk ewes. 



The reciprocal cross was made the next year by crossing a 

 Suffolk ram with 20 Dorset ewes. Description is given of the first 

 cross F t ; of the second generation F 2 in which the F x ram described 

 was mated with 28 F x ewes, and of the horned F 2 ram which was 

 mated with 6 pure Dorset ewes, with hornless Hampshire ewes and 

 with F 2 ewes. The hornless F 2 ewes were tested by mating them 

 with the F 2 hornless ram already proved to be pure hornless. Two 

 horned ewes which appeared in the second generation have been 

 tested by mating them with a Dorset horned ram ; figures are given 

 of the progeny of the speckled faced F 2 ram mated with F x ewes. 

 From these experiments the following conclusions can be given: 

 i) As far as the characters under observation are concerned 



