396 A YEAR OF COSTA RICAN NATURAL HISTORY 



five-eighths inches or less in length, were taken with a small 

 water net from a bit of sandy bottom over which the current 

 was upstream as the result of a partial whirlpool due to a 

 curving of the stream-bed. The larvae lived entirely buried 

 in the sand. A. found that merely skimming the surface 

 of the sand was unsuccessful, but by taking the sand to a 

 depth of half to three-quarters inches the larvae were secured. 

 On placing them in a bottle of water with sand at the bottom 

 they frequently stood end on, head in the sand and tail up, 

 and they probably take the same position in the stream-bed. 

 At other times they assumed the horizontal position in the 

 sand, completely covered by it, and the only indication of 

 their presence was when a grain of sand suddenly rose in 

 the water, probably as the result of a slight spouting of water 

 from the rectum in the respiratory process. They moved 

 swiftly through the water in the bottle from time to time, 

 returning to the sand. They also burrowed rapidly through 

 the sand with the legs, throwing sand out behind. We were 

 never able to keep these Progomphus larvae alive in captivity 

 for more than a day or two, which is no doubt correlated 

 with their habit of burying themselves in sand under swiftly 

 flowing water. 



Near where the road forded the Surubres stood a small 

 trapiche or sugar mill, not in use at this season, and along the 

 river bank below the ford was a cane field surrounded with 

 tangled masses of a morning-glory or "churristate." The 

 trapiche having a roof, was a favorite place of retreat if we 

 were collecting near it, when we were caught in a shower or 

 the sun grew too hot. The lovely bit of shady road was a 

 delight, with its banks hung with maidenhair ferns of at 

 least five species, Selaginellas of at least three kinds and the 

 whole luxuriant drapery shot through with begonias — be- 

 gonias with tall red stems, smooth, thick rounded leaves and 

 red or white flowers; begonias with hairy pointed leaves and 



