NO. 6 MYERS AND WADE: NEW WEST COAST FISHES 153 



not in the least affect the edibility of the fish killed, nor is a concentration 

 lethal to fish poisonous to terrestrial vertebrate animals, including man, 

 which drink the water. Moreover, organic decay destroys the effect of 

 the derris after a few days. The dust of powdered derris does, however, 

 have a very irritating and narcotic effect on the mucous membranes of the 

 eyes, mouth, and nasal passages, and the user must exercise some care. 

 Most of these remarks apply equally to the South American timbo, which 

 is also now loosely called derris or "rotenone." 



The senior author took a supply of both timbo and derris (powdered 

 root, 5% rotenone content) on the 1938 cruise. These were put up 

 before the trip in small cellophane sacks, three of which could be packed 

 together in a watertight one-pound coffee tin. The cellophane and tins 

 protected the powder sufficiently from damp, which quickly ruins the 

 potency of the powder. One or more of the tins was taken ashore at 

 each collecting place. 



The powder was used as follows : After selecting a tide pool of reason- 

 able size, the sacks were taken from the tin and the contents of one sack 

 was dumped into the tin with some water and shaken vigorously until the 

 mixture was of the consistency of thin, smooth, liquid mud. This was 

 poured into the pool and stirred into all its recesses. Fish soon began to 

 wobble and gyrate. If no effect was seen within a few minutes, another 

 sack was used. One one-third pound sack was usually sufficient for a 

 tide pool approximately 12 by 6 feet and two feet deep, but some soaking 

 is necessary to produce the full effect, which seems to be reached in a half 

 to one hour. At Academy Bay, a very large tide pool, of perhaps 25 by 

 100 feet, and from a foot deep at its margins to three feet deep at its 

 center, was poisoned with less than two pounds of derris. This was far 

 too weak a dose, and some fishes were still alive three hours later, but 

 probably nine-tenths of the individual fishes were killed. Over a thousand 

 fishes were taken from this one pool, and thousands more were discarded 

 for lack of containers and preservative. 



In the Galapagos pools, the Pomacentrids were the first fishes to be 

 affected and killed, while some of the gobies and Eleotrids, notably 

 Bathygobius and Eleotrica, resisted all but very strong derris. The fishes 

 that habitually hide under stones, such as Ogilbia, and especially those 

 that make burrows beneath large rocks {e.g., certain Ophichthyid eels), 

 take some time to come out, probably merely because the derris does not 

 reach them at once. Some fishes float when killed, others sink. The two 

 tiny, brilliant, banded gobies described by Snodgrass and Heller as Gobius 

 rhizophora and Gobius gilberti, form cases in point. The former, much 



