STONE-FLIES. 265 



the efifect of wliich against the light-brown grey body and 

 wiDgs is very remarkable, as the insect flutters heavily from 

 spot to spot. The membranous envelope within which the 

 eggs are contained is exceedingly delicate, so that it shows 

 both the shape and colour of the eggs which it encloses. The 

 egg-cluster of Perla unarginata is about as large as a swan- 

 shot, and nearly as black. It is rather more barrel-shaped 

 than globular, and, on being examined with a lens, is seen to 

 be composed of several hundred eggs, agglutinated together in 

 a sort of semi-order, as if the eggs had been deposited in strings, 

 and the strings wound at random into a ball. 



These eggs are deposited in the water, and when hatched, 

 the young larvae manage to crawl under stones and similar 

 sheltered localities. They prefer running to still waters, and 

 the more rapid parts of the stream to tliose which are com- 

 paratively still. In the swift river Dove these creatures are 

 very plentiful, and I used to capture almost any number of 

 them in the spring time, the rippling, eddying stream exactly 

 suiting them. Near my present house is a very small pond, 

 through which a stream of water continually runs. It is mar- 

 vellously rich in insect life, and I have captured in it a variety 

 of aquatic insects in all stages, which utterly astonish those 

 wlio are not initiated in the wealth of entomology. Yet, 

 though I have industriously fished every inch of this pond, I 

 have never found the larva of the Stone-fly. Larvae of May- 

 flies, Dragon-flies, Caddis-flies, Dyticus, Acilius, Gyrinus, Noto- 

 esta. Gnats, and other aquatic creatures, I take in plenty, but 

 not one single Stone-fly larva have I found, though I have 

 sedulously examined both the inlet and outlet of the stream 

 which runs through the pond and keeps it supplied with water. 



In the present genus, the abdomen is very stout, and has 

 two long slender appendages at its tip. The wings of the male 

 are very short in proportion, and altogether he is quite an 

 inferior being to his stately mate. There are several species of 

 this group in England, some of which are known to anglers by 

 various popular names. The name of Stone-fly is, however, 

 given indiscriminately to at least four species. One is that 

 which has already been mentioned ; another is scientifically 

 known as Perla grandis ; a third is Perla cephalotes, which, as 

 its name implies, has a very large head ; and a fourth, perhaps 



