964 Cuartes Paut ALEXANDER 
molt up to the time of pupation. Here the dorsum of the body is a dirty 
brownish green with more or less distinct brighter spots, and the venter 
is bright green in color. The mouth parts and the attachment apparatus 
are as in the second stage. 
The pupa is comparatively active, moving about by flexion of the 
abdomen. Its usual position is vertical, with the tips of the breathing 
horns just reaching the surface of the water. This vertical position the 
pupa maintains by grasping the vegetation with its caudal abdominal hooks. 
At times the pupa descends beneath the water by clinging to the vegetation, 
but a submergence of six hours causes asphyxiation. The pupal existence 
was determined by Miall and Shelford as eleven days. When the adult 
emerges, the cast pupal skin is left attached to a moss leaf by the dorsal 
abdominal projections at the posterior end of the body. 
Larva.— Length, about 25 mm. 
Young larvae distinctly greenish, especially on ventral side, this coloration caused, at 
least in part, by contents of alimentary cana! showing thru body wall; older larvae more 
opaque, brownish green in color; dorsum with an indistinct striping of brown and whitish; 
ventral surface whitish. 
Head entirely retractile within prothorax and usually so retracted except when larva is 
feeding; opening transverse. Prothorax, viewed from above, roughly rounded, anterior 
margin convex; on ventral surface traversed by a weak suture. Meso- and metathorax 
narrow. Abdominal segment 1 indistinctly divided into two annuli, the more basal one 
very narrow; abdominal segments 2 to 7 divided into a narrow basal ring and a much broader 
posterior ring, each of these annuli still further subdivided into two annulets. Body pro- 
vided with numerous elongate trachea-bearing filaments, both simple and branched, giving 
larva avery bristly appearance (Plate LX X XIII, 448), these spines arranged as follows: tergites 
with both simple and bifurcated filaments; on posterior part of pronotum two short, simple 
filaments; on meso- and metanotum, two pairs of simple filaments; on abdominal segment 
1, an anterior pair of simple, and a posterior pair of deeply branched, filaments; segments 
2 to 7 with basal ring unarmed, posterior ring with an anterior pair of simple, and a caudal 
pair of deeply branched, filaments; segment 8 with only a branched pair, anterior branch 
long, slender, posterior branch very small, its outer face heavily chitinized and forming 
dorsal lobes of spiracular disk; plewrites with all the filaments simple; one on posterior part 
of prothorax, and on anterior part of each of the other two thoracic segments; posterior 
filament on these latter nearly vestigial; two unequal filaments on first abdominal segment; 
segments 2 to 7 with one filament on basal ring and two on posterior ring, the anterior one 
the longest; segment 8 with a single rudimentary filament; sternites with all the filaments 
simple; prosternum without filaments; meso- and metasternum with a strong filament near 
lateral margins; abdominal segment 1 with two pairs of filaments, posterior pair the longer 
and more widely separated; segment 2 with three pairs of filaments, anterior pair very short; 
segments 3 to 7 with four pairs of filaments and an additional median one, arranged as follows: 
