130 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 



Colors. — Back, brownish olivaceous, with bright silvery reflections; 

 lower parts silvery white; fins orange or red. Head and operciila pro- 

 fusely spotted with round black spots, numerous to the tip of the snout, 

 all along the top of the head, above the eyes; the gill-covers scarcely as 

 numerously or regularly spotted as the other parts. Back and sides 

 freely spotted with black spots of irregular shape, some being star- 

 shaped, others X-shaped; more numerous and irregular near the tail. , 

 Dorsal, adipose, and caudal profusely spotted with oval. Scales firmly 

 adherent. 



Diagnosis. — From S. lewisi by its large head, more slender form, , 

 much larger scales, more numerous spots, and more forked tail. From i 

 ^S. virginnUs by its strongly forked tail and spotted head; anal destitute ; 

 of spots. From >S'. masoni by its small scales. (For further diagnosis ; 

 see those species.) 



IlAB. — Streams along the w est coast of California northward. The • 

 foregoing' summary of specific characters was based on a specimen i 

 labelled by Dr. Ayres, of San Francisco, as belonging to his species ^8'. . 

 rivnlaris; on a large specimen from Chico Creek, California; on two > 

 obtained at the Dalles of the Columbia; and on one obtained from > 

 the Deschutes River, Oregon. These have been selected as type speci- 

 mens out of a vast nund^er from the same and intermediate localities. 

 All the true brook-trout found west of the Mississippi are distinguished i 

 by their black spots, the red spotted being either lacustrine or anadro- 

 mous, and therefore hardly coming under the name ''brook-trout," al- 

 though often ascending streamlets to spawn. 



Two varieties of the S. irklea seem to prevail, as follows : 



First variety. — In general shape and form resembling the type of 8- ' 

 iridea. Colors pale, the fish having a washed appearau(!e. Spots on a 

 caudal and dorsal faint. Half a dozen specimens were s(Mit from San 

 Mateo, California, by Mr. R. D. Cutts. The type of this variety is entered I 

 in Mus. Catalogue Fishes, 597, labelled " variety lavatus:^ 



Second variety— stelJatns.— The star-spotted trout. This was described 

 by Dr. Girard as a distinct species, under the name -of Fario steUatus.^ 

 Most of the specimens I have examined have a double row of teeth om 

 the vomer. It is principally distinguished from the type form of S. iridea < 

 by the greater profusion, size, and irregularity of its black spots. Thei 

 young frequently show large spots, of a more regular roundish shape.' 

 It may be one of the effects of age in the species iridea that the black 1 

 spots fade out. The same seems to occur in individuals of the species 

 described by us as S. hrevicauda. I 



As a comparison of the relative size of the heads of the black-spotted ( 

 trout seems to furnish valuable data for classification, the following table 

 has been introduced. Two sets of measurements are given, the one 

 showing the number of times the length of the head, when measured 

 from snout to the scales at the nape, is contained in the total length of 

 the fish; the other when the head is measured from the snout to the 



