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?LORATION3 ix COLORADO AND UTAL ?. oq.&to'ten times flowed over some field, while, the bed' of many considerable leave, Rie-Alamosa, etc.) are filled with dry clay and dust. tn%Iiers of trout , in many cases .thonsand&of_themi. Asa-..3utothese irrigs.'- ? _'ate left to perish- in the fields. - The destraction:_or trout-by this agency tliari that due to all others combined; and it is going on, in almost every.ditch in Colorado. easy to suggest a remedy for it The valleys in quostion would be worth- Sgr3uulture were it not for irrigation, and the economic value of the trout.. si'trrfle as compared with the value of the water privileges. It is apparently ible to shut out the trout from the ditches by any system of screens. These ssoon become clo„ged by silt, dead leaves, and sage brush, and thus will not 3 the passage of the water.. ' Psffios£=of the trout are lost by entering the ditches in the fall when run- - - , sift. down, stream with the cooling of the water. It has been suggested that a law epmpel the closing of the ditches after the 'barvest, allowing the streams to flow - ill-_ttatil March or April. In the fall the water is worth most to the fishes and ° €e#4e farmers. I am unable to say whether this plan will prove: practicable or This is certain, that if the present-eonditious_ go on. the trout in the lower, ill the streams will be exterminated, and there will be trout only in-the in kes and in the mountain meadows, to which agriculture can not extend 1NDIGENIOi1S FItIHES. Y es of Colorado are very few in number, notwithstanding the fact the. four ?zaal basins are within the limits of the_4tate.. trout;. S'almo mykiss Walbaum, and its varieties are found h all the mountain d`strea%us, down to a point where the summer-te.mperature_r_eaches W to 650t gradually disappear. In clear streams and streams with bottoms of gravel stend much farther than in turbid streams or those with clay bottoms. ' -inountain minnows, Rhi.nichthys dulcis, on the eastern slope and in the Rio Oi4$e, and 4gosia yarroui, in the Colorado basin, accompany the trout in the mount- >'?aeadows, not, however, ascending so near to the sources of the stream. On the other _hand, they extend their range farther down than the trout,;and exist in millions in the upper part of some of t lie valleys. They seem to be harmless little fishes, and they are eaten by the trout. :the blob or Miller's Thumb (Cottus bairdi punetulatus) is equally fond of cold atrft,clear waters. Iu the Colorado basin it is very abundant, but in the other regions it ? ree, if present, and we did not find it. It is very destructive to the eggs of rrcnE . _"Ohe suckers of various species extend up the rivers more or less to the point _ Wire the trout disappear. Generally speaking, the suckers of the different basins are uolike. We found Ca.tostoaau.? griseus and Cato8twnI18 teres in the Platte, the for- raer;asaending the streams much higher than the latter. In the Arkansas, CatoWwnus r > tSj jn the Rio Grande, Pantosteis plebeius; in the Colorado, Pantosteus delphinus, omus latipinnis, and _Yyra.uchen cypho. The species of Catostomus and Tyrauchen considerable size, and are food-fishes of poor quality. All are destructive to I1$`e1'rgs of the trout. -