WERNER MARCHAND 87 



other aquatic plants, having little or no current in ordinary stages. 

 The same process of sifting was repeated June 25, and not a single 

 larva was found. Individuals placed in breeding cages failed to 

 transform. A pupa was collected June 30, from which the imago ap- 

 peared July 17. A cast pupal skin was also picked up July 18. Sev- 

 eral imagos were taken in the same locality between May 23 and 

 June 22. 



During the winter good sized larvae sometimes occurred in dip-net 

 collections, and March 18 they were again found to be common at 

 Hart's Station C, in loose drifts, partly frozen, left by an early spring 

 rise. The previous year they were common in April far from the 

 margin, among sticks, logs, and other drift, marking the higher stage 

 reached by the water on March 19 of that year. These situations 

 remained moist for a long time, harboring a large variety of aquatic 

 forms, some of which completed their transformations successfully 

 while others apparently failed, the river remaining low and the 

 weather dry. 



Hart's description of the mature larva (Plate 3, Fig. 41) is as 

 follows : 



^' Larva, Mature. — Length 45-55 mm., diameter 6-7 mm. Transparent 

 whitish with a greenish tint, marked with conspicuous dark brownish or greenish 

 fuscous, paler in younger specimens." 



"Lateral prothoracic striated areas less than half as long as the dorsal, stria- 

 tion microscopically fine and opaque or scarcely shining, a small smooth spot on 

 the anterior margin of the striated area, resting on the lower lateral line; remain- 

 ing upper lateral areas of thorax much more coarsely and sparsely striate and 

 shining; middle and lower thoracic areas — often much reduced, or even entirely 

 covered by the lateral stripes — with distinctly finer and closer striation, but 

 still shinmg; abdominal lateral areas with still finer striation, nearly as fine as 

 that of the prothorax and feebly shining; dorsal and ventral areas all smooth 

 and shining, rarely a few broken striae about their margins, at the base of the 

 prothorax or on the anal segment." 



"Dark annuli distinct, broad, including false feet, transverse pale spot imme- 

 diately in front of dorsal tubercles narrow or closed up in the mature larva; on 

 the abdomen above, each annulus usually extends back on the median line in a 

 triangular prolongation, often nearly attaining the next annulus, less developed 

 in younger larvae. Prothoracic lateral space occupied in front of the striated area 

 by a dark opaque quadrate spot, extending from the anterior annulus. Lateral 

 stripes of meso- and metathorax broad, at least the upper ones widened poste- 



