FISH FAUNA OF LAKES OF SOUTHEASTERN OREGON. 97 
CoMPARISON OF CERTAIN DIsTINCTIVE CHARACTERS OF RUTILUS THALASSINUS, R. OREGONENSIS, 
R. coLUMBIANUS, AND R. Brcoror—Continued. 
Scales above lateral line. 
— > = — = — 
Species. | 10. | lL. 12. 13. 14. | Species. 10. 11. 12° | 13. 14. 
| = = ee 
R. thalassinus-.... 5 47 6 US eee | R. columbianus...-|--..--.- 17 21 1 eee 
R. oregonensis. ....|.....-.. 24 109 54 | 6:}| Robicolor== 2222-2 9 10 Uo eee tes] Bexanece 
Dorsal rays. 
paid; “ake i - | eae. 5-1 OMe 
Species. 7. 8. 9. Species. 7. 8. 9. 
eee — = | a 2 = 
Us HAIRSSINUSS — cco. ces cess eee | ees eee CON lek Columbians. oe. eee eee eee | en ce | 9 35 
Rooregonensiss .- == 2 soc. ene ceeeecs: | uy) 130 (iV | TP o} (clo) (2) pe Fes Ee ee de eh ee 14 6 
Anal rays. 
Species. 7 8. 9 10. i. Species. Te 8. 9. 10. hk 
R. thalassinus..... 1 46 IDA nee is Soe R. columbianus.. - | saeceoce 43 Ul bevaems oll caos 
R. oregonensis. -..- | 54 135 3 1 | 1 || R. bicolor......... | 5 Tih Seer Wei (be es ae 
Rutilus symmetricus (Baird & Girard). 
Drew Creek, Muddy Creek, and Cottonwood Creek, in Lake County, Oreg. 
This species is to be distinguished from R. thalassinus by its shorter head, more slender body, 
and more nearly horizontal lower jaw. The dorsal fin is inserted posterior to the ventral, while in R. 
thalassinus it is almost immediately above it. Individuals of the species are not known to grow so large 
as those of R. thalassinus, and while specimens of the two species may occasionally be taken together, 
the latter generally prefers deeper and more quiet water. 
An examination of specimens from Drew Creek along with others from Putah Creek, in a distant part 
of the Sacramento Basin, shows that the former usually have fewer dorsal and anal rays and shorter fins. 
The peculiar character of the Drew Creek examples is further maintained by a comparison with individuals 
from Napa River and from the streams tributary to San Francisco Bay. Careful measurements4 of many 
specimens from the latter basin demonstrate that the fins of the males are generally much longer than 
those of the females, the difference being especially pronounced in the pectorals. The same sexual 
difference is also to be found in representatives from Drew Creek and other streams. 
TABLE SHOWING COMPARATIVE LENGTH OF FINS AND NUMBER OF DorRSAL AND ANAL RAYS IN 
SPECIMENS OF RUTILUS SYMMETRICUS FROM DIFFERENT LOCALITIES. 
Drew Putah | Napa Drew | Putah Napa 
Creek. Creek. River. Creek. | Creek. River. 
Seen eee ace eee 2 10 
oe Be asco ee eenoere acces |-ocasacnae 1 5 
Length ventral: 
CS Oe age ean opted 
AE e ae i 
Dorsal rays: 
8 
a Snyder, J. O., Report Bureau of Fisheries 1904, p. 332. 
b The 0.20-0.21 line divides females and males. 
