320 
BULLETIN OF THE BUREAU OF FISHERIES 
9. Moxostoma aureolum (Le Sueur). Red-fin mullet; red-horse sucker. 
RECORD OF CAPTURE 
Only one specimen was taken each year by the Shearwater, the first at the 
mouth of Beaver Creek on July 11, 1928, in a meter net at 6 meters below the surface, 
and the second near Angola on August 6, 1929, at the surface in water of 11 meters. 
Although mostly an inhabitant of large streams, it is moderately common in Lake 
Erie. 
DESCRIPTION 
The red-fin mullet larva suggests that of C. commersonii in general characters 
but is readily distinguished by the foreshortening of the body before the vent, 
myomeres numbering only 24 plus 13 while in the common white sucker there are 
33 plus 10. 
7 .5 -millimeter stage .■ — Total length, 7.5; standard length, 7.1; length to vent, 
5.0; greatest depth, 1.2; diameter of eye, 0.5. Myomeres, 24 to vent plus 13 behind. 
Low dorsal embryonic marginal fin fold originating over tenth myomere behind head 
and a slight cell concentration at its beginning indicating the later location of true 
dorsal; ventral marginal originating in advance of dorsal and much deeper anteriorly. 
Figure 22. — Moxostoma aureolum, 7.5 millimeters 
identical with dorsal behind vent; pectorals moderate, extending more than halfway 
to posterior margin of air bladder; caudal lophocercal. Mouth moderate, terminal, 
upper jaw somewhat projecting, suckerlike; eye moderate; snout almost as long as 
eye; interorbital space wide; air bladder large, one-chambered at this young stage. 
Pigmentation. — Small black chromatophores are evenly distributed over head, 
followed by a double uneven line of very large stellate ones widely separated from 
each other on dorsal aspect, numbering about 26-35. From midline of eye back- 
ward there appears a subsurface series of many black chromatophores crowded into 
a continuous line on either side of head, merging into a large black patch over top 
of air bladder, then continuing along dorsal aspect of intestine to vent and beyond 
along underside of tail almost to caudal. On underside of stomach region is a very 
unequal double series sparsely distributed to about middle of intestine, and a few 
more near the vent. A double line of small chromatophores appears on ventral 
aspect from vent to caudal, but there are very few chromatophores on the caudal 
itself. On ventral aspect, subsurface chromatophores are similar to those on sides 
of head, starting behind eye and extending backward to meet those at anterior 
margin of air bladder. 
The specimen immediately suggests the young of Catostomidx in general char- 
acters. It differs, however, from C. commersonii in several respects, especially in a 
myomere count of only 37 contrasted with 43 or more in the latter species. The 
foreshortening occurs before the vent, having only 24 myomeres in this region while 
the common sucker has 33-35. The indications are that the dorsal fin will be short and 
