438 INSECTA. 



Agbioit, Fab. 



Where the wings are elevated perpendicularly when at rest, the head is 

 transversal, and the eyes are distant. 



The other Subulicornes have an entirely membranous or very soft mouth, 

 composed of parts that are rather indistinct. Their tarsi consist of five 

 joints; their inferior wings are much smaller than the superior, or even 

 wanting, and their abdomen is terminated by two or three setae. 



They form the genus 



Ephemera, Lin. 



So called from their short term of life, in their perfect state. Their body 

 is extremely soft, long, tapering, and terminated posteriorly by two or three 

 long and articulated setae. The antennse are very small and composed of 

 three joints, the last of which is very long, and in the form of a conical 

 thread. The wings of those Insects are always placed perpendicularly, or 

 slightly inchned posteriorly, like those of an Agrion. 



The Ephemera usually appear at sun-set, in fine weather, in summer and 

 autumn, along the banks of rivers, lakes, &c., and sometimes in such in- 

 numerable hosts that after their death the surface of the ground is thickly 

 covered with their bodies; in certain districts cart-loads of them are collected 

 for manure. The descent of a particular species — the albipennis — re- 

 markable for the shortness of its wings, recals to our minds a heavy fall of 

 snow. 



These Insects (our May-Flies) collect in flocks in the air, flitting about 

 and balancing themselves in the manner of the Tipulse, with the terminal 

 filaments of their tail divergent. 



The continuation of their species is the only function these animals have 

 to fulfil, for they take no nourishment, and frequently die on the day of 

 their metamorphosis, or even within a few houi's after that event. Those 

 which fall into the water become food for Fishes, and are styled manna by 

 fishermen. 



If however we trace them back to that period in which they existed as 

 larvae, we find their career to be much longer, extending from two to thi-ee 

 years. In this state, as well as that of seminymphs, they live in water, fre- 

 quently concealed, at least during the day, in the mud or under stones, 

 sometimes in horizontal holes divided interiorly into two united canals, each 

 with its proper opening. These habitations are always excavated in clay, 

 bathed by water, which occupies its cavities; it is even supposed that the 

 larvae feed on this earth. 



The seminymph only differs from the larva in the presence of the cases 

 which enclose the wings. Wlien the moment of their development has ar- 

 rived, it leaves the water, and having changed its skin, appears under a new 

 form — but, by a very singular exception, it has still to experience a second 

 change of tegument. 



The ultimate exuvium of these Insects is frequently found on trees and 



