C. E. Beecher — Origin and Significance of Spines. 259 



The large palmate antlers act as sounding boards, and, when 

 listening, the animal holds his ears in the focus of the anterior 

 surfaces of the antlers. 



The hollow-horned mammals afford some of the most evi- 

 dent examples of the use of horns for protection and offense. 

 In species with permanent horns, like the bison, oxen, goats, 

 cattle, antelopes, etc., the horns are generally present in both 

 sexes, though in the males they are often much the larger. In 

 defense, many of the horned ruminants hold the head down, 

 thus protecting the nose and bringing the top of the skull into 

 prominence. In this position, the horns are most effective. 

 A similar posture is taken by the horned batrachians and 

 lizards. 



The Porcupine and Echidna rely largely on the protection 

 afforded by their spines, and on this account they are sluggish 

 in their movements, and make little effort to escape approach- 

 ing enemies. 



Many of the great horned Dinosaurs of the Mesozoic are 

 well provided with an armature of protective plates and spines 

 on various parts of the body. In addition to an armature on 

 the body, Triceratoys™ had three large horns on the head, one 

 median (nasal) and two lateral (supra-orbital). These were 

 powerful offensive and defensive weapons. There were also 

 other small nodes and spiniform ossicles around the posterior 

 crest of the skull and on the jugals, forming a part of the 

 general armor. In Stegosaurus,*' the efficient offensive and 

 defensive weapons were the huge spines on the tail, and it is 

 interesting to note as a parallel to this condition, that the 

 greatest nerve centers were in the sacrum, and therefore pos- 

 terior also. 



No group of vertebrates shows such a variety of protective 

 and offensive characters as the fishes. Many of the older types 

 were heavily plated, while in others the tin-spines were greatly 

 developed. Among modern forms, the protective character of 

 the spines is well shown in types like the Spiny Box-fish, 

 Chilomycterus geometricns and JJ'wdon maculatus. A combi- 

 nation of mechanical and optical protection is afforded in 

 the remarkable Australian Pipe-fish, Phyllopteryx eques' 5 

 (figure 49). This fish has numerous spines and ribbon-like 

 branching filaments, the former giving it a mechanical defense, 

 and the latter assisting in its concealment among sea-weeds, to 

 which it bears a striking resemblance. 



Spines for protection are extremely common among insects, 

 even in larval forms. They have been so frequently noted as 

 to require no elaboration here. Packard 54 has ably discussed 

 the origin of nodes, tubercles, and spines, among certain cater- 

 pillars. Among the forms which feed exclusively at or near 



