44 PACKARD, 



On the 24th of September some young larvae, one- 

 fourth the size of the adult, were found, at which date, 

 however, most of the larvae were pupating, the semipupee 

 being found in the thin cases. On the same date several 



O 



pupse were found in which the fly was nearly ready to 

 appear. A male imago appeared Oct. 9, and a female 

 Oct. 14, 1867. During the last of April of the present 

 year (1868) we found the same larva in abundance among 

 the green filamentous weeds at low-water mark, so that 

 there are undoubtedly two broods in a year ; the first 

 brood of flies. appearing in the early summer, the second 

 brood appearing late in the autumn, and the species 

 undoubtedly passes the winter in the larva state. 



The head seen from above is nearly square, being a 

 little longer than broad, with a pair of simple eyes of 

 unequal size situated a third of the distance from the 

 anterior to the posterior end of the head, and with a few 

 bristles on the head. The two-jointed antennas (Fig. 1, 

 ) are well developed, the basal joint being quite stout. 

 The labrum (Fig. 1, 6) is transversely ovate; the man- 

 dibles (Fig. 1, c) are long, much incurved, and serrate on 

 the inner edge ; the maxillae are obscurely developed, 

 forming a fleshy, two-jointed tubercle. The labium 

 (Fig. 1, d) is somewhat triangular and multidentate on 

 the anterior edge (indicates the oesophagus.) This larva 

 differs from a fresh-water larva of this genus from Lake 

 Champlain, in not having the three 3-jointed filamentous 

 appendages inserted just above the anal legs. (See also 

 Westwood's figure 124, in his Classification of Insects, 

 vol. ii.) 



After the larva has become mature and ceases eating, 

 it retires within its rude case, and there awaits its trans- 

 formations. The first signs of the presence of the grow- 

 ing pupa are the enlargement of the thoracic segments, 

 especially the mesothoracic, and at the same time the 

 compound eyes of the fly can be seen just behind the 

 two simple eyes of the larva, and the legs of the fly can 

 be seen through the transparent larva-skin. They are very 

 long and doubled up on the sides of the body. The 

 pro-thoracic legs are quite separate from the two posterior 



