196 A YEAR OF COSTA RICAN NATURAL HISTORY 



on to a big rock. This being a hopeful indication of near 

 transformation we carried it back to the cabin, where we 

 rigged up an ingenious and home-like stream for him in a 

 dish aided by a stone and a bottle. We subsequently took 

 him to Cartago but the ungrateful little beast seemed un- 

 appreciative and died July 25 or 26. In March the supposed 

 Thaumatoneura larvae were not rare on the rock face of the 

 nearer waterfall, where there was a thin layer of organic 

 mud subjected to only a moderate amount of spray. No 

 doubt the larvae are often carried by the dripping water 

 lower and lower down from the roots in which the eggs are 

 laid. But none of these March larvae transformed in our 

 possession. On April 24 at the same fall we found a score 

 of the exuviae or skins of these larvae shed at the time of 

 transformation to the adult, while smaller larvae than those 

 indicated by the exuviae were crawling over the rocks. On 

 April 26 the long search was crowned with success by finding 

 two larvae in the act of transformation into Thaumatoneura 

 adults. 



One of these larvae was hanging on the wet slippery face of 

 the fall in such a position that a small projection above it 

 gave it shelter from the direct spray. The wings, while 

 they hung limp and wet, in fact until they were full size 

 and dry, were green. The body of the dragonfly was brown 

 and green and as the creature hung on the rocks, the body 

 and wings giving the little trembling jerks that usually 

 accompany the growing or "filling out" of a transforming 

 insect, the likeness to a green leaf on a stem trembling in the 

 breeze was very marked. There was much small-leaved 

 Commelina on the face of the fall as well as some delicate 

 grasses, both of a bright pea green, and we ourselves fre- 

 quently confused the Thaumatoneura with one or other of 

 these if we happened to move our eyes from it. It certainly 

 seemed to be a good case of protective coloring. Other full 



