332 



EVOLUTION AND ANIMAL LIFE 



them are further armed with fangs connected with a venom 

 gland, so that to most animals their bite is deadly. Besides 



Fig. 192. — Cocoon enclosing a pupa of the great Ceanothus moth, Samia ceanothi, 



spun by the larva before pupation. 



its fangs the rattlesnake has a rattle on the tail made up of a 

 succession of bony clappers, modified vertebrae, and scales, 



by which intruders are warned of its pre- 

 sence. This sharp and insistent buzz is a 

 warning to animals of other species and 

 perhaps a recognition signal to those of its 

 kind. 



Even the fishes have many modes of 

 self-defense through giving pain or injury 

 to animals who would swallow them. The 

 catfish or horned pout when attacked sets 

 immovably the sharp spine of the pectoral 

 fin, inflicting a jagged wound. Pelicans 

 which have swallowed a catfish have been 

 known to die of the wounds inflicted by 

 the fish's spine. In the group of scorpion 

 fishes and toad fishes are certain genera 

 in which these spines are provided with 

 poison glands. These may inflict very 

 severe wounds to other fishes, or even to 

 birds or man. One of this group of poison 

 fishes is the nohi (Emmydrichthys). A 

 group of small fresh-water catfishes, known 

 as the mad toms, have also a poison gland 

 attached to the pectoral spine, and the 

 sting is most exasperating, like the sting 



Fig. 193. — Larva of swal- 

 lowtail butterfly, Pa- 

 pilio cresphontes , 

 showing osmateria 

 (eversible processes 

 giving off an ill odor) 

 projected. (After 

 photograph by Slinger- 

 .land.) 



