86 BULLETIN OF THE BUREAU OF FISHERIES. 
Rutilus thalassinus (Cope). 
Cottonwood Creek, Oreg.; Muddy Creek and Goose Lake, Lake County, Oreg.; Pitt River near 
Alturas; Pitt River near Canby and Pitt River in Big Valley, Cal. 
Cope @ recognized two closely related species of Rutilus (Myloleucus) from Goose Lake, both of 
which are no doubt referable to the same form which he describes under the name Mylolewcus thalas- 
sinus. This species is not to be confused with Rutilus symmetricus occurring in the same basin, nor 
should it be identified with the Myloleucus parovanus of Cope? from Beaver River, Utah. 
R. thalassinus may be distinguished from each of the species of Rutilus here described by its longer 
fins. It further differs from R. bicolor in having a larger head, a more posterior location of the dorsal 
fin, and in usually possessing one more dorsal ray; from R. oreyonensis in having larger scales, there 
being fewer in the lateral series, in the series before the dorsal fin and in those above the lateral line, 
and also in having one more dorsal ray; from R. columbianus in having a greater number of scales in the 
lateral series and a lesser number between occiput and dorsal fin. These differences are set forth in 
greater detail in the tabulated comparisons of the four forms, page 94 et seq. 
As at present understood, this species is confined in its distribution to the Sacramento basin, this 
being the first account of its occurrence beyond the confines of Goose Lake. It is to be searched for in 
bayous, deep quiet pools, and sluggish streams. 
MEASUREMENTS OF SPECIMENS OF RUTILUS THALASSINUS FROM Pitt RIVER NEAR CANBY, LASSEN 
County, Cat. 
| | 
Menethiol hodyaces--s=2-—-—— sens mm..} | 100 | 106 116 | 103 93 101 
Length head ... eel 26 229) | 2 -28 27 -28 
Snout to occiput o2) -225 | 21 22 <21 22 
Snout to dorsal... | .56 -59 | -58 58 - 60 -58 
Snout to ventral -54 -59 -55 -58 -58 587 
Depth body....---- +28 -31 | -28 -30 28 -30 
Depth caudal peduncle 4 -2 -125 | -12 13 12 -125 
Length snout........- -085 | .09 -08 09 -08 -085 
Length maxillary - -08 -09 | -08 | -09 -08 -085 
Diameter eye.....-. ae -055 -055 - .06 06 06 -06 
Interorbital width -. aoe -09 -10 -10 -09 -10 -10 
Height dorsal......- 21 -23 -21 | real 21 23 
Height anal --. 185 -19 -18 -18 17 -19 
2 200 2k 18 -20 18 -20 
Length ventral. . -175 18 -16 18 AT -18 
Length caudal. ..- SOR | 00239 -30 -30 28) Parag 
Seales lateral line. ....-- 50 51 | 49 51 48 51 
Scales above lateral line - - ll iL il 1 ll ll 
Seales below lateral line - - 6 6 6 6 7 5 
Seales before dorsal. -.-. 26 25 29 26 27 25 
Dorsal rays-- ae 9 9 9 9 9 9 
JAPA eV Re osetia aoe one e ccm Sees 8 9 8 8 8 8 
| 
| | | | | 
Mength of bod ye -- ~-------—- en mm... 99 86 86 82 S40 78 73 106 | 137 
ON GN) NCA Caer e te eee -28 +29 -28 | 29 ry || ae -29 -28 | -28 
Snout to occiput. . as 25 23 -21 | 23 22 | 24 24 22 | 22 
Snout to dorsal... 59 59 -o7 58 -o7 -59 59 58 | 57 
Snout to ventral 58 56 -56 56 -57 56 -60 -o7 58 
Depth hod yseecs-s sae 30 30 -30 29 -28 -2f | .30 -29 } 31 
Depth caudal peduncle. -13 -13 -13 13 115 2124), F8 -13 135 
Length snout....-.-...-- | .08 - 095 -08 -085 -08 -08 | .09 -09 -085 
Length maxillary - 085 «095 -08 -09 -08 08 -09 -08 -08 
Diameter eye... ..- 06 07 -06 -065 .065 075 | 07 -06 -055 
Interorbital width 10 10 -10 -10 09 s10m |) 0) -10 -10 
Height dorsal... -- -23 24 -23 23 -21 | 122 | 196 =220 21 
Height anal..... 19 19 -18 19 -18 | 18 19 -18 18 
Length pectoral. 20 22 -20 20 -18 19 18 -19 185 
Length ventral.. 18 -19 19 -18 -16 18 | .175 17 -175 
Length caudal. - -33 33 ~32 -330) «31 | £32 -33 -3l | -31 
Seales lateral line. . 47 49 47 50 50 | 47 46 46) 51 
Scales above lateral line 1L 12 12 il 11" il ll il il 
Seales below lateral line. - = 5 6 6) 6 5 | 5} 6 6 6 
Seales before dorsal... .-- | 24 26 26 25 26 | 26 j 23 25 25 
Dorsal rays. .-.- = 9 9 9 9 9 9) 9 9 9 
Anal! rayScz/2os5o20- Sh Aes ee ee | 9 9 8 8 | 8 8 8 8| 9 
aCope, E. D., Proceedings Academy Natural Sciences Philadelphia, 1883, p. 143-144. Cope’s supposition that he had 
in hand 2 distinct species was probably due to the poor:preservation of his specimens. He says (p. 139): “I fished for a 
day with hook and line without success, but procured a good collection of fishes by another method. I found numerous 
specimens both fresh and dry, which had been dropped by fishing birds on or near the shore.’’ 
bCope, E. D., Proceedings American Philosophical Society, Philadelphia, 1874, p. 136. 
