MAY-FLIES. 91 



and the species are red, black with blue spots, or greyish brown ; 

 the smaller species expand less than an inch. They fly little, and 

 are generally found resting on rushes and other plants by the side 

 of water. We have but one other British species of this sub- 

 family, Platycnemis Pennipes, Pall., which differs from any others 

 in the tibiae being slightly dilated. 



In the genus Mecistogaster, Ramb., the stigma is of irregular 

 shape; the wings are long, and the body is slender, and fre- 

 quently of great length. M. Lucretia, Drury, is a common South 

 American species (blackish, with yellow markings), which measures 

 five inches across the wings, which are transparent, with a dusky 

 cloud at the tips. It is six inches in length, looking as if the 

 abdomen was twice the proper length. M. Linearis, Fabr., which 

 we have figured, is rather smaller. The genus Megaloprepes has 

 broader wings and a shorter body than Mecistogaster. M. Cceruleata, 

 Drury, from Central America, measures nearly six inches across 

 the wings, and nearly four inches in length. The body is blue 

 above, and the wings are transparent, with a broad blue band across 

 each near the tip. This species is one of the largest dragon-flies 

 known in expanse of wing. 



EPHEMERID^E. 



Wings not folded in repose ; hind wings much smaller than 

 the fore wings, sometimes wanting ; mouth imperfectly developed ; 

 abdomen furnished with two or three long slender filaments; 

 larvae and pupae aquatic, probably feeding on decaying vegetable 

 matter at the bottom of the water. 



The Ephemeridce, called otherwise May-flies, or Day-flies, or 

 Brown and Green Drakes, are well known to every observer of 

 Nature who has wandered by the side of a stream in summer ; 

 and they are specially interesting to anglers, as they are a very 

 favourite food of river fish. To the entomologist also they present 

 many points of interest. The winged insect which quits the pupa- 

 case is not the final form of the species, but an intermediate stage, 

 called the subimago. The insect, after flying away from the 

 pupa, settles and casts off yet another skin before it appears in its 

 full development. Although the perfect insect takes no food, 

 and lives only a very short time, and in some cases only a few 

 hours, yet the earlier aquatic stages of its life are known to last at 

 least two or three years. The Epliemeridm often appear in extra- 

 ordinary numbers, and Dr. Hagen states that in some parts of 



