46 



with Ephemerae and Phryganese. Dr. H. A. Hagen has quoted from a letter to the late 

 Professor Agassiz, from Mr. George E. Woodwell, of the Tribune Office, Chicago, 111., 

 July 23, 186 (?) as follows :— 



" I send you a number of specimens* of a fly which annually visits our lake-cities, 

 and which has the present summer appeared in larger swarms than ever known before. 

 During the recent hot nights they have poured in from the lakes in myriads, rendering it 

 necessary in lighted buildings to close the windows and doors in order to escape their 

 visitation. For several nights past they have thus swarmed upon us, and the morning 

 would witness about the posts of the street lamps large heaps, in some instances three 

 inches deep, and covering an area of two or three yards square." 



Such times are the grand festivals of the finny tribes, when they become fat and well 

 liking. 



The Stone Fly (Perla). 



Cotton's quaint description of this insect is as follows : — 



" Having told you the time of the Stone-fly's coming in (from the middle of April to 

 the end almost of July,) and that he is bred of a cadis in the very river where he is 

 taken, I am next to tell you that this same Stone-fly has not the patience to continue in 

 his crust or huskf till his wings be full grown, but so soon as ever they begin to put out, 

 that he feels himself strong (at which times we call him a jack,) squeezes himself out of 

 prison, and crawls to the top of some stone, where if he can find a chink that will receive 

 him, or can creep betwixt two stones, the one lying hollow upon the other, which, by the 

 way, we also lay so purposely to find them. He there lurks till his wings be full grown, 

 and there is your only place to find him, and from thence doubtless he derives his name ; 

 though, for want of such convenience, he will make shift with the hollow of a bank, or 

 any other place where the wind cannot come to fetch him off. His body is long and 

 pretty thick, and as broad at the tail almost as in the middle ; his colour, a very fine 

 brown, ribbed with yellow, and much yellower on the belly than the back ; he has two 

 or three whisks also at the tag of his tail, and two little horns upon his head. His wings, 

 when full grown, are double, and flat down his back, of the same colour, but rather darker 

 than his body and longer than it, though he makes but little use of them ; for you shall 

 rarely see him flying, though often swimming and paddling with several feet he has under 

 his belly, upon the water, without stirring a wing." Comp. Ang., Part II., ch. 8. 



In England four insects at least belonging to the Perlina bear the name of " Stone- 

 fly." Their specific names are Marginata, Grandis, Cephalotes, and Bicaudata. 



The female Stone-fly has the habit of carrying her bundle of eggs about with her 

 between the candal setse (which Cotton calls "the whisks at the tag of her tail"), and 

 this for some time before depositing it in the water. The mass is as large as a swan-shot, 

 and black. Seen under the microscope the individual eggs resemble dark brown oval 

 capsules, with projecting fibres at one end denoting the point of egress for the larva. 



Mr. P. H. Gosse, in his Canadian Naturalist, speaks of the Perlina as "Water-flies," 

 and alludes to them, under different dates, from the beginning of April to the middle of 

 of July. 



Hellgrammite (larva). Horned Corydalis (imago). (Corydalis cornutus.) 



Corydalis cornutus is the monarch of the Water-flies. I well remember the admira- 

 tion with which I first looked upon the weird beauty of this remarkable insect, Fig. 6, 

 represents the female with the wings expanded ; Fig. 7, c, the male with the wings 

 closed. The undulating body, dark and glabrous ; the plated thorax, the square head, 

 the powerful mandibular ; the projecting eyes, black and bead-like f the long setaceous 

 antenna? ; the wonderful wings, smoked yet transparent, flecked with white, nerved and 



* The letter contained dry specimens of Ephemera natata. 



t Observe that Cotton is here confusing the larva of the Stone-fly with that of Phryganea, to be presently 

 described. 



