348 
BULLETIN OF THE BUREAU OF FISHERIES 
Pigmentation. — Chromatophore marking is not heavy but limited principally 
to snout, top of head, a wide dorsal series (3-6 lines wide) to caudal, and a single 
series along lateral line to caudal, in which the spots are rather close together, being 
round anteriorly and more linear posteriorly. Many occur also below the surface 
over stomach-intestinal region, followed by a double surface series on dorsal ridge 
from vent to caudal, spreading rather widely around anal base. There is a subsurface 
concentration at base of caudal. A few chromatophores are evident on dorsal and 
many on caudal. 
BREEDING 
The fat-head minnow spawns throughout the summer, at which time the head of 
the male becomes jet-black, the caudal peduncle dusky, and the snout covered with 
about 14 coarse tubercles. Greeley (1927) reported spawning on June 22. The 
round opaque eggs, one-sixteenth inch in diameter, were attached side by side in a 
mass to the underside of a stick immersed in 8 inches of water at a temperature of 
67° P. There were approximately 700 eggs in the mass. 
27. Campostoma anomalum (Rafinesque). Stone-roller minnow. 
RECORD OF CAPTURE 
Although straying rarely into Lake Erie, the stone-roller minnow frequents 
warm, shallow streams. 
DESCRIPTION 
The remarkably elongate intestine which winds in spiral fashion around the air 
bladder is peculiar to Campostoma. The differences between this species and Semo- 
tilus atromaculatus atromaculatus, with which it is readily confused, are discussed 
on page 329. 
9. 7 5 -millimeter stage . — Total length, 9.75; standard length, 9.2; length to vent, 
6.35; length of head, 1.9; diameter of eye, 0.7; greatest depth to vent, 1.3; depth 
behind vent, 0.6 millimeter. Myomeres, about 24 to vent plus 14 + behind. Mar- 
ginal fin fold frayed but probably arising over air bladder and extending to caudal, 
low; somewhat broader ventrally; caudal heterocercal with rays forming. Body 
moderately elongate at this stage; snout obtuse; mouth small, terminal; perito- 
neum black. 
Pigmentation. — Black chromatophores are heavy on lips, snout, top and sides 
of head, and in a double series of about 50 on dorsal ridge. These ridge chromato- 
phores are exceptionally large and have about 3 other rows between the double 
