82 THE BUTTERFLY VIVARIUM. 



which do not undergo a perfect metamorphosis. In 

 the larvse of Butterflies and Moths they are very 

 conspicuously situated above the feet in the side of 

 each segment, and generally surrounded by an iris 

 of a very distinct colour ; they are in Caterpillars 

 generally eighteen in number. In the larva of the 

 Gnat, however, and also in many that have the fore 

 part of the body buried while feeding, the breathing 

 apparatus is situated near the tail. 



The aquatic larvae of some of the Ephemera 

 breathe by means of delicate feather-like branchiae 

 analogous to those of certain Molluscs. These 

 branchial organs are sometimes arranged along the 

 sides, and in others placed at the tail, as in the case 

 of the larva of the purple-winged Dragon-fly. In 

 these arrangements there are many modifications, 

 and the branchiae serve occasionally the double pur- 

 pose of a breathing apparatus and a fin-like means 

 of locomotion. 



The Means of Defence of larvae are in some 

 instances curious. Some have the faculty of drop- 

 ping from a branch as though dead when ap- 

 proached, spinning at the same time a web like 

 that of a Spider, cither to break their fall or to serve 

 as a means of re-ascent when the danger is over, 

 though I have never observed the web to be made 



