JUAN FIN AS— THE WATERFALLS 205 



be of indifferent use and value. Many larvae lose them by 

 accident or by the bite of a brother or other enemy and yet 

 pass their larval existence as tranquilly, and accomplish 

 their transformations as successfully, as their brethren 

 which, like the foxes in the fable, retain their brushes. Three 

 of these peculiar larvae found May 2 in the outflow from the 

 farther waterfall possessed their caudal gills which were 

 most odd-looking. They appeared as if cut off straight 

 across at the tip, instead of tapering as usual, the straight 

 edge then scalloped into three points. Each inflated-look- 

 ing gill was one-fifth as long as the short "pudgy" body, 

 giving the larva a "tail-heavy" appearance. When first 

 taken into the hand these three larvae remained motionless, 

 "playing 'possum" as it were, for a minute or two, and 

 then took to their legs with some speed. In spite of their 

 double equipment of gills these larvae did not frequent a 

 different abiding place from others less richly "engilled," 

 their fellow inhabitants being larvae of Hetarina, Argia and 

 common types of Libellulines. 



These larvae died before transforming but were preserved 

 in alcohol; a microscopic examination of their rudimentary 

 wings showed so close a correspondence with the veins of 

 the wings of the adult dragonfly Cora chirripa, captured at 

 the same waterfall, as to leave no room for doubting that 

 these larvae are of that species. It is the presence of the 

 ventral gills that gives these larvae their great interest, for 

 breathing organs in such positions are rare in dragonfly 

 larvae generally, although common enough in may-fly and 

 Sialid larvae. It has been suggested that they correspond 

 to the legs of the hind part of the body of centipedes and 

 their allies, which some consider to represent the ancestors 

 of insects. The adult Cora chirripa has a body one and 

 seven-eighths inches long, the thorax pale greenish or bluish 

 with black lines on its sutures and a broad black stripe on 



