VARIATION 



Meristic variation in horns. 1 These appendages afford good 

 material for studies in variation. They sometimes consist of 

 horny matter (cattle, sheep, rhinoceros, etc.) and sometimes of 

 true bone, as in the deer. They sometimes persist through life 

 (cattle, sheep, goats, etc.) and sometimes are periodically shed, 

 as with the antlers of the stag. They sometimes, as in cattle, 

 have a bony case, which is a true outgrowth of the skull, but 

 often, as in the rhinoceros, they have no connection whatever 

 with the bone beneath. Again, the antlers, which are bony, sep- 

 arate with a clean scar from the bone of the skull, as a leaf 

 stem parts from its twig. 



The meristic variations of horns are no less remarkable than 

 their substantive variations just mentioned. They are for the 

 most part symmetrically placed in pairs on either side of the 

 skull just above the eyes, though the horn of the rhinoceros is 

 borne upon the nose and therefore upon the median line. 



Variation in number occurs either symmetrically or asymmet- 

 rically. If the rhinoceros has an extra horn it will be just 

 above and on the median line with the normal. Sheep may have 

 an extra pair just external to (behind) the normal, 2 or there may 

 be three on one side and two on the other. In the latter case the 

 third horn will be a little one lying between the normal and the 

 more ordinary extra horn. In still other cases, according to 

 Bateson, a double core will be found incased in a kind of 

 "double-barreled" single horn. 



Among cattle no increase in the normal number of horns is 

 known to the writer, but their entire absence is common. 

 Indeed, the readiness with which the polled character appears is 

 astonishing, 3 particularly as it is associated with a peculiar prom- 

 inence (the poll) lying between and often slightly below the 

 normal base of the horns. In cattle, meristic variation in horns 

 seems to be associated neither with divided horns or extra 

 prongs. 



1 Bateson, Materials, etc., pp. 285-287. 



2 Four-horned breeds are not unknown. Bateson, Materials, etc., p. 285. 



8 It is a well-known fact that if either parent be polled the horns are almost 

 certain to be absent in the offspring, and Storer, in his Wild White Cattle of 

 Great Britain, says there is evidence that these park cattle have been several 

 times alternately polled and horned since their inclosure in the parks. 



