382 
BULLETIN OF THE BUREAU OF FISHERIES 
snout short and depressed over eye, interorbital space flat; mouth small, oblique, with 
maxilla just reaching forward margin of eye. 
Pigmentation. — The body is evenly covered with small black chromatophores 
which follow margins of myomeres. The marking is heavier around jaws, top of 
head, and cheeks. Single linear spots occur along lateral line from above origin of 
anal to caudal, and around bases of dorsal and anal. Only the belly is colorless. All 
fins have chromatophores, fewer on ventrals and pectorals. 
BREEDING 
The common sunfish is a nest builder, using its fins to hollow out a depression in 
the mud or sand. The male carefully guards the nest and fearlessly drives off intrud- 
ers. During the breeding season his colors become much more brilliant, and the 
ear flaps are conspicuous. 
51. Ambloplites rupestris (Rafinesque). Rock bass; goggle-eyed bass. 
RECORD OF CAPTURE 
The rock bass is found very generally about weedy places on the lake shore and 
in most of its tributaries. Many young were taken by seines in the Niagara River 
and alongshore, but none was taken in the surface towings farther out in the lake. 
DESCRIPTION 
The robust, compressed shape of the rock bass resembles other sunfishes, but the 
large mouth, 5 or 6 anal spines, and 10 to 12 dorsal and anal soft rays distinguish it 
immediately from others. 
10.5-millimeter stage . — Total length, 10.5; standard length 8.9;length,to vent, 5.0; 
length of head, 3.1; snout, 0.35; diameter of eye, 1.1; greatest depth before vent, 
3.18; depth behind vent, 2.3 millimeters. Myomeres, 13 to vent plus 18 behind 
(only 14 well developed). Body oblong, much compressed; caudal peduncle stout; 
eye large; large mouth terminal, oblique, maxilla past vertical from anterior margin 
of pupil; lower jaw barely projecting. 
Pigmentation. — The fish is covered by large stellate black chromatophores, 
especially on tip of both jaws, massed over snout and top of head, and in heavy 
dorsal and ventral series along margins of body and around fins. The chromatophores 
are more openly arranged on dorsal half and posterior half behind the vent. The 
