366 HABITS AND INSTINCTS OF ANIMALS. CHAP. XI. 



and figures, no less than eight of these are small 

 shrimps, or crustaceous insects, all excessively minute. 

 The Gammarus caudisetus (fig. 90.), for instance, in 

 its natural size, is scarcely larger than a pin's head. 

 Gam. heteroclitus is about two tenths of an inch long. 

 Another annulose animal (fig. 91.), which he does not 



seem to have described in the text, is a striking proto- 

 type of a caterpillar, closely resembling, by its tail, 

 some of the Sphingides, or hawk moth tribe. He also 

 includes among the number of these luminous animals, 

 two very small star-fish : the others belong to the An- 

 nelides, or red-blooded worms, and to the fixed polypes. 

 Thus it would seem that phosphorescent animals occur 

 in all the great divisions of those which are inverte- 

 brate, and sanction the opinion that this faculty is given 

 to a far greater number of the inhabitants of the deep 

 than is generally imagined. 



(368.) It has been supposed, by two well-known 

 entomologists *, that the luminosity of land insects may 

 be given them as a means of defence from their ene- 

 mies : we think, however, that this idea is not borne out 

 by analogical reasoning. The chief enemies of insects 

 are birds; and these are at rest at those hours when 

 luminous insects are abroad and active. The owls and, 

 the goatsuckers are the only nocturnal birds which feed 

 after sunset : but the former live upon much larger in- 

 sects than those we have mentioned ; while the latter 

 always seek their game at a much higher elevation in 



* Kirby and Spence, Int..to.Ent. 



