FISHES OF SACRAMENTO-SAN JOAQUIN BASIN. 187 
16. Rutilus symmetricus (Baird & Girard). California Roach. 
Pogonichthys symmetricus Baird & Girard, Proc. Ac. Nat. Sci. Phila., 1854, p. 136, San Joaquin River, Fort Miller, 
Algonsea formosa Girard, Proc. Ac. Nat. Sei. Phila., 1856, p. 183, Merced and Mojave rivers. 
Leucos formosus Jordan & Henshaw, Wheeler Survey, p. 193, 1878. 
Rutilus symmetricus Jordan & Evermann, Fishes North & Mid. Amer., pt. 1, 245, 1896. 
Head 4.1 in body; depth 4.4; eye 3.6 in head; interorbital and snout equal, 3 in head; depth of 
head at occiput 1.5 in its length. Teeth 5-4, long and hooked, the 5 being on the left side; scales 
12-51-7, dorsal 10, anal 9. (Measurements on a specimen 86 mm. long from San Joaquin River at 
Pollasky.) 
In general the head is small and conical, 0.25 to 0.27 of body; depth of body 0.23 to 0.25 of its length; 
mouth small, lateral cleft.slightly oblique, anterior cleft horizontal (not arched), lower jaw included, 
more or Jess trenchant, and its tip often covered with a horny sheath; eye rather large, its diameter 
0.06 to 0.07 of body, almost wholly in anterior half of head; snout broad and blunt, nostrils farther from 
each other than from tip of snout; the lower jaw with a horny or cartilaginous sheath. Ventrals 
inserted in middle of body, reaching to vent; dorsal of 10 rays, its origin slightly behind ventrals, 0.58 
to 0.60 of body length from tip of snout, its longest ray 1.2 in head; anal inserted under last ray of dorsal, 
of 9 or sometimes 8 rays; caudal very large, its length one-third that of body, widely spread, with 10 
rudimentary rays, deeply forked, the middle rays 2.3 in longest, upper lobe slightly longer than lower. 
Seales 12-48 to 51-7 or 8. Color, dusky above, gradually changing to silvery on belly, cheeks silvery, 
the fins nearly colorless, but the rudimentary caudal rays quite dusky. A dark stripe along middle of 
side is sometimes faintly separated from the dusky color of the back. (Description is based on several 
specimens, the largest 5 inches long, from San Joaquin River at Pollasky, about 2 miles from Fort Miller, 
the type locality.) 
The head varies from 0.24 of the body in specimens 67 mm. long from North Fork Consumne 
River at Pleasant Valley, and another 85 mm. long from Thomas Creek to 0.28 in a specimen 46 mm. 
long from North Fork of Pitt River. The size of the head in the 96 specimens measured may be stated 
in tabular form as follows: 
Size of head: Specimens. Size of head: Specimens. 
LS ean Se ae RE Ee aE Sa ER SS 2 5 13 
0.245. . 1 21 
0.25... 24 1 
0.255... 3 1 
OG egslan oncavincad estas os qaaenedecans wesc codesews sunt 30 
The typical form has the head 0.27 or 0.26. Such are found in San Joaquin River at Pollasky 
(type locality); also in Kings, St. John or Kaweah, Tule, Chouchilla, and North Fork Merced rivers, 
and in Merced River at Benton Mill and Livingston. Specimens from Battle Creek, Stanislaus 
River, and Mariposa Creek have the head 0.26 or 0.25, and specimens from Thomas Creek and North 
Fork Consumne River have the head 0.25 or 0.24; but the size of the head does not correspond with 
other variations. The Thomas Creek and Consumne River specimens do not at all resemble each 
other, while the Mariposa specimens and those from North Fork Merced River do look much alike. 
The eye usually measures 0.07, but is often much smaller. In specimens from Battle Creek it is 
0.07 or 0.065; from Thomas Creek 0.065 or 0.06; North Fork Merced River 0.06, rarely 0.065 or 0.055; 
Mariposa Creek 0.055, rarely 0.06 or 0.05. The greatest variation in one locality is that of Merced River, 
at Benton Mill, from 0.055 to 0.07. The tip of the lower jaw is scarcely rounded and not arched. It is 
often more or less trenchant, and is frequently tipped with a sheath that is sometimes cartilaginous and 
sometimes horny. The bony sheath is deciduous in preserved specimens, which accounts for its appar- 
ent absence in some instances. It resembles that of Acrocheilus, but the cutting edge is thinner. 
It is present in all the specimens from North Fork Consumne River and in half those from North Fork 
Merced and from San Joaquin at Pollasky. Only a few of the specimens from the Stanislaus River, 
Merced at Livingston, Chouchilla River, and Mariposa Creek have the horny sheath; and it is entirely 
wanting in specimens from Battle Creek, Thomas Creek, and Merced River at Benton Mill. The 
teeth are 54, but sometimes4—4. The scales of the lateral line vary from 47 to 56, the greatest variation, 
48 to 56, being found in specimens from Mariposa Creek. The number above the lateral line is 
usually 12 or 13, but varies from 11 to 15; below lateral line 6 or 7, sometimes 8. 
