258 C. K Beecher — Origin and Significance of Spines. 



(figures 42,43), and probably arose through gradual specializa- 

 tion according to the law of multiplication of effects, acted on 

 by the agency of sexual selection. In some species, as the 

 Reindeer (Rangifer tarandw), the differentiation of the antlers 

 has secondarily produced a useful structure. One of the brow- 

 tines in this species has become greatly enlarged and palmated, 

 and serves to assist in removing the snow to uncover food. 

 Evidently this has had something to do with the common 

 retention of the antlers in both sexes. 



42. 



43. 



HTTYT j 



Figure 41. Antler of Gervulus (?) dicranoceros. Pliocene. 

 Figure 42. Antler of Cervus pardinensis. Pliocene. 

 Figure 43. Antler of the Fallow Deer (Cervus dama). 

 Reduced. (After Nicholson and Lydekker.) 



Certain types of horns are common to particular regions, 

 especially when the cattle are in a semi-wild state, as in the 

 Western Plains of America. The Texas cattle have long, 

 gently curved horns standing out from the head. Similar 

 forms are prevalent in the cattle of southern Italy and in other 

 warm temperate regions. Farther north, the horns become 

 more curved in a direction parallel with the head, and are 

 therefore closer to the skull. The most northerly representa- 

 tive of the hollow-horned ruminants, the Musk-Ox (Ovibos 

 mochatus) has the horns hanging down close to the skull and 

 only curved outwards in their distal portions. Marsh suggests 

 to the writer that these variations in the directions of the horns 

 have been influenced by the climate. A warm climate per- 

 mits the horns to stand out directly from the skull. Farther 

 north, or in a colder region, the frequent freezing of the horns 

 and their consequent drooping has induced a natural drooping 

 condition, and an Arctic climate has resulted in the production 

 of horns closely appressed to the skull, in which position they 

 cannot be affected by freezing temperatures. 



Another possible service for antlers is also suggested by 

 Marsh. As is well known, the male Moose is one of the most 

 wary of the Cervidae, and detects noises at great distances. 



