130 EEPOET OF COMMISSIONER OF FISH AND FISHERIES, 



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 Colors. — Back, brownish t)livaceous, with bright silvery reflections; 



lower parts silvery w^hite; fins orange or red. Head and opercula 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. 



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

 nmch larger scales, more numerous spots, and more forked tail. From 

 S. virginalis 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.) 



IIab. — Streams along the west coast of California northward. The 

 foregoing summary of specific characters was based on a specimen 

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

 rividnris', on a large specimen from Chico Creek, California; on two 

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

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

 mens out of a vast number from the same and intermediate localities. 

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

 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 8. iridea 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 appearance. Spots on a 

 caudal and dorsal faitit. Half a dozen specimens were sent from San 

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

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



Second rarietij — steUatns. — 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 on 

 the vomer. It is i^rincipally distinguished from the type form of /S'. iridea 

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

 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 

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

 described by us as 8. hrevicaiida. 



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 



