RESEMBLANCES AMONG ANIMALS. 71 



cealed. One of the uses of the phosphorescence with 

 which many insects are furnished, is probably to 

 frighten away their enemies ; for Kirby and Spence 

 state that a ground beetle (Carabus) has been observed 

 running round and round a luminous centipede as if 

 afraid to attack it. An immense number of insects 

 have stings, and some stingless ants of the genus Poly- 

 rachis are armed with strong and sharp spines on the 

 back, which must render them unpalatable to many of 

 the smaller insectivorous birds. Many beetles of the 

 family Curculionidse have the wing cases and other ex- 

 ternal parts so excessively hard, that they cannot be 

 pinned without first drilling a hole to receive the pin, 

 and it is probable that all such find a protection in 

 this excessive hardness. Great numbers of insects hide 

 themselves among the petals of flowers, or in the cracks 

 of bark and timber ; and finally, extensive groups and 

 even whole orders have a more or less powerful and 

 disgusting smell and taste, which they either possess 

 permanently, or can emit at pleasure. The attitudes of 

 some insects may also protect them, as the habit of 

 turning up the tail by the harmless rove-beetles (Sta- 

 phylindidaa) no doubt leads other animals besides chil- 

 dren to the belief that they can sting. The curious 

 attitude assumed by sphinx caterpillars is probably a 

 safeguard, as well as the blood-red tentacles which 

 can suddenly be thrown out from the neck, by the 

 caterpillars of all the true swallow-tailed butterflies. 



It is among the groups that possess some of these 

 varied kinds of protection in a high degree, that we 



