C f 3 



2. ROCK DAY-FLY. 

 EPHEMERA RUPESTRIS. 



Plate 8. 



The Antlers have a multitude of clofe-connec~ted joints, and grow 

 all the way fmaller to a point. 



The Bristles at the Tail are fhort, and weak. 



Nothing can be ftranger than the hiftory of this Fly, which came 

 to my knowledge by an accident laft year ; and, I believe, has not 

 been obferved by any writer. 



On a ftone obelifk, erected before a houfe in London, to fupport 

 the lamp, I obferved feveral oblong, greyifh tubes, or cafes, running 

 in various directions ; fome ftrait, and others a little bent. I mould 

 have fuppofed them the tubuli, or cafes of Sea Worms, petrify 'd, as 

 is frequent in many kinds of ftone ; but that thefe obelifks carried 

 very plainly the marks of the duffel ; and the little tubules I obferv- 

 ed were wrought over them ; and therefore evidently had been formed 

 after the ftone was work'd. 



The Angularity of this, caufed me to direct a fervant to pick off 

 fome of them ; which he attempted in vain : he found them as hard 

 as the reft of the ftone, and fixed to it with great firmnefs : with 

 the help of a hammer, fome few were at length got off; and 

 I found nothing fhelly in them; but that they were mere ftony 

 tubes, form'd of the matter of the obelifk, in fmall granules, ce- 

 mented clofe. 



In breaking feveral others, I at length found in fome, the creature 

 which had form'd them for its houfe and fhelter : this was a little 

 yellowifti Worm, with a black head, and a number of fmall, fhort 

 feet. It ufually refided in the bottom of the tubule -, but came out 

 at pleafure. 



On fome cobwebs, about the upper part of the obelifk, I found, 

 among other Infects, the remains of two or three Flies, feeming 

 either of the Day-Fly, or Moth kind ; but too imperfect for me t© 

 afcertain the Species. 



C 2 Thus 



