20 Em-maun — A Nnv Trout from Lower California. 



sea; the other streams reach the sea only at times of flood and 

 for an irregular period following rainy seasons. They some- 

 times disappear entirely during long dry periods. At the time 

 of Mr. Nelson's visit (last of July, 1905), the San Ramon River 

 at Rancho San Antonio was about 10 feet wide and 10 inches 

 deep in the middle of the channel, where the current was about 

 6 miles an hour. 



The San Pedro Martir Mountains are made up of a friable 

 granite and the bed of the stream is granite, sand and gravel 

 with many boulders often of huge size. About 12 miles above 

 the San Antonio ranch there is a high waterfall beyond which 

 fishes can not go in ascending the stream. Previous to the 

 winter of 1903-4 then' were several large pot-holes in the stream 

 close to San Antonio in which trout were plentiful. During 

 that winter there were excessively heavy rains in this region 

 and the floods in the river brought down great quantities of 

 boulders and other debris, filling the pot-holes in the lower por- 

 tion of the canyon. The result of this was to destroy the haunts 

 of the trout in that portion of the stream, so that trout are now 

 found only sparingly in the vicinity of San Antonio. Several 

 miles further up the canyon some pot-holes still exist in which 

 trout are reported to lie numerous. Trout occur in some num- 

 bers from a short distance below San Antonio up to the falls 

 already mentioned, or throughout a distance of about 12 miles. 

 The portion of the stream in which they occur is, according to 

 Mr. Nelson, wholly below the limits of the pine forests. Near 

 San Antonio only small trout are found, hut higher up trout 12 

 to 15 inches long are said to occur. Tin 1 largest examples seen 

 by Mr. Nelson, however, did not exceed S inches in length. 

 From his own observations and from information obtained from 

 residents of the region, Mr. Nelson is convinced that the heavy 

 floods referred to destroyed a considerable percentage of the 

 trout in this stream. 



The Cyprinodonts in the collection were obtained in a small 

 stream winch Hows from large springs at San Ignacio, or ap- 

 proximately in north latitude 27° 10'. These springs rise just 

 above the town of San Ignacio and produce a permanent stream 

 about 30 feet wide and a foot deep which Hows through a nar- 

 row valley for 10 or 12 miles before the water is lost in the 

 sand. This water course extends to the sea and during rainy 



