148 BULLETIN OF THE BUREAU OF FISHERIES. 
SUMMARY ON DISTRIBUTION. 
Of the 27 species listed above, 14 are limited to California; 6 (Hntosphenus 
tridentatus, Lampetra cibaria, Salmo irideus, Salvelinus malma, Gasterosteus cata- 
phractus, and Cottus asper) have more or less ability to withstand sea water and 
are not of interest when studying the distribution of fresh-water fishes. 
Of the 22 strictly fresh-water species, 12 (Catostomus occidentalis, Orthodon 
microlepidotus, Lavinia exilicauda, Mylopharodon conocephalus, Pogonichthys macro- 
lepidotus, Ptychocheilus grandis, Leuciscus crassicauda, Leuciseus conformis, Rutilus 
symmetricus, Archoplites interruptus, Hysterocarpus traskvi, and Cottus gulosus) are 
typical of and have a wide distribution in the basin; 3 (Catostomus muacrops, 
Cottus asperrima, and Cottus macrops) are limited in distribution and known 
only from their type localities; Rutilus bicolor is common to Pitt River drainage 
and to the lakes and streams of southern Oregon; and 5 (Pantosteus lahontan, 
Catostomus tahoensis, Leuciseus egregius, Agosia robusta, and Cottus beldingii) are 
Nevada species that have crossed the Sierras into the Sacramento-San Joaquin 
Basin. 
The last 6 mentioned need particular notice. 
Besides being widely distributed in the Pitt River region, Rutilus bicolor is 
exceedingly abundant in Wolf Creek (<Indian Creek <North Fork Feather 
River), Indian Valley. The connection between this stream and Pitt River is 
not very close, as they are tributary to the Sacramento at points about 300 miles 
apart. 
Agosia robusta is the only one of the Nevada species that has become widely 
distributed west of the Sierras. 
Leuciscus egregious is limited to the vicinity of Big Meadows (headwaters of 
North Fork of Feather River), and to one locality on the opposite side of the basin 
near Clear Lake. 
Catostomus tahoensis has been found only in the vicinity of Big Meadows and in 
Sierra Valley, though the streams connecting these two places have been fished in 
several places. : 
Pantosteus lahontan has been found only in Big Meadows vicinity. 
Cottus beldingii only in Cole Creek, tributary to Sierra Valley. 
The Big Meadows region has 4 Nevada species, Sierra Valley 3, 2 being common 
to both. The former has 2 not found in the latter, and the latter has 1 not found 
in theformer. It seems probable that there have been at least two migrations from 
the Lahontan drainage into the Sacramento, though there is need of more data 
on that point. 
The following table indicates the distribution according to the above summary. 
By Lahontan division is meant the Big Meadows and Sierra Valley regions. The 
Sacramento division includes the whole basin except that included in the Lahontan 
and Pitt River regions. 
