THE SIALINA. 213 



furnished with a pair of small compound eyes_, and 

 with long antennae^ but is quite destitute of ocelli, 

 although most of the other species of the group 

 possess those organs; the tarsi are composed of five 

 joints, of which the fourth is considerably dilated. 

 Such is the general appearance and strnctm-e of the 

 Sialis lutarms, the only British example of the tribe 

 of the SiALiNA, an insect well known to the angler as 

 a bait. 



The female Sialis deposits a multitude of little 

 cylindrical eggs, with a short appendage at the top 

 like the neck of a bottle, upon the surface of plants 

 growing in or overhanging the water, and these are 

 placed so close together, that they form a continuous 

 brown coat upon the leaves or stems on which they 

 are deposited. The larvae hatched from these eggs 

 are furnished with six legs, and with seven or eight 

 pairs of slender jointed filaments along the sides of 

 the abdomen, which not only act as respiratory organs, 

 but also enable them to swim freely in the water. 

 When mature, the larva burrows into the banks of its 

 aquatic residence, and forms there a comfortable little 

 chamber, in which it undergoes its change to the 

 pupa state, and which it does not quit until it has 

 arrived at its complete development. 



f Still by the water-side, clinging in complete repose 

 to the stems of aquatic plants, or to the grasses 



' which fringe the banks of the stream, or occasionally 

 hovering on unsteady wings over its surface, we meet 



\ with a number of flies of no particular beauty, but 

 which, from the peculiarities of their structure and 

 habits, are of considerable interest to the entomolo- 



