INTERDUNAL PONDS AND TAMARACK SWAMPS 169 



minnow, and the shiner. There are also present some clams, 



notably Lampsilis luteola, Alasmodonta marginata and Anadonta 



grandis, the first confined to the very new ponds, the other two 



occurring also in those somewhat older. There are found, too, 



such insects as the caddis worm (Go era) 



(Fig. 176) nymphs of the damsel flies of the 



genus Lestes and of the dragon flies Tramea 



lacerta and Celethemis eponina, the water 



boatman, and occasional diving beetles that 



fly, frequently seeking new territory in which 



to hunt. The caddis-fly, damsel-fly, and 



dragon-fly nymphs are characteristic, the 



others cosmopolitan. 



The damsel-fly nymphs are long, slender, 

 and bear three diverging gill plates at the 

 posterior end of the body. Nymphs of Lestes ^^'^'" ^''''^' Enlarged. 

 (Fig. 177) are recognized by the form of the so-called accessory 

 jaws (Fig. 178), really labial palps, on the extensible mask 

 of the head, which is the much modified lower Hp or labium. 



Fig. 176.— Caddis-fly 



1 



1 



Fig. 177. — Nymph of damsel fly, Lestes for cipatus. Enlarged. After Needham 



Each ''jaw" has two processes, "one of them resembling a 

 fork with the median tines broken off, the remaining process 

 consisting of a long non-bifurcate projection with a short, hairy 

 hook at the distal end and minute teeth along the mesal margin." 

 The nymph of Tramea lacerta is green with brown markings. 

 The legs are long and thin. The spines of the eighth and ninth 

 segments are very long. The nymphs of C. eponina (Fig. 179) 



