112 UNIVERSITY OF COLORADO STUDIES 



Considering the data, it seems proper to refer the Colorado specimens to the 

 subspecies Boleosoma nigrum mesaeum (Cope). 



Boleosoma nigrum mesaeum (Cope) (Fig. 51) 



Poecilichthys mesaeus Cope, Proc. Acad. Nat. Sci. Phila., p. 232, 1864 (Platte River near Fort 

 Kearney, Nebraska). 



Boleosoma nigrum mesaeum (Cope) — Jordan and Evermann, Bull. 47, U.S. Nat. Mus., p. 1059. 

 1896. 



Body elongate, not much compressed; depth 4. 6 to 6 in the length to the base 

 of the caudal; head rather large and broad; top of the head somewhat flattened, 

 width of the head i . 5 to almost 2 in the length of the head, which is 3 . 8 to 4.25 

 in the length of the body; eye large, situated above the middle of the side of the 

 head, center of the eye nearer to the tip of the snout than to the posterior margin 

 of the operculum by almost the length of the snout; dorsal margin of the eye 

 higher than the flattened top of the head; diameter of the eye greater than the 

 interorbital distance, barely equal to or usually less than the length of the snout, 

 3.5 to 5, usually 4.25 to 4.5 (see Table VII), in the length of the head; snout 

 short and blunt; mouth terminal, slightly oblique, lips rather fleshy, lower included 

 by the upper; angle of the mouth barely if at all reaching the level of the anterior 

 margin of the eye; premaxillaries protractile; operculum with a heavy spine, 

 directed caudally on a level with the lateral line;' base of the spinous dorsal shorter 

 than that of the soft dorsal, soft dorsal scarcely separated from the spinous dorsal, 

 base of the first ray of the soft dorsal inserted slightly behind the level of the 

 ventrals, spines VIII or IX, rays 12 or 13; pectorals large; ventrals small, of I 

 spine and 5 rays; anal small, of I spine and 8 or 9 rays, base of the spine behind 

 the level of the first ray of the soft dorsal; caudal large, fan-shaped, not forked; 

 scales rather small, closely imbricated, strongly ctenoid, with about 16 basal radii, 

 4 or 5, 42-54, 7 to 9; cheeks scaled or naked. 



Color above greenish brown to dusky; mid-dorsal region with 4 or 5 saddle- 

 shaped bands of dark brown which extend down each side for two or three rows of 

 scales; lateral line crossed by 10 or more irregular black marks which often 

 resemble the letters W, M or N; below this row of marks another of smaller 

 blotches usually present, these alternating with those crossing the lateral line; 

 most of the scales above the lateral line and many below it outlined with dusky, 

 giving the entire fish more or less of a reticulate pattern; ventral parts yellowish 

 or pinkish white, somewhat sprinkled with dusky; top of the head dark; a rather 

 conspicuous dusky bar extending from the tip of the snout to the anterior margin 

 of the eye and a less prominent bar below the middle of the ventral margin of the 

 eye; opercular region dusky, usually with a dusky spot; rays of the soft dorsal, 

 caudal, and to some extent the ventrals, crossed by rows of dusky spots which give 



■ One indvidual, 63 mm., Boulder Creek 6 miles east of Boulder, July 25, 1912, had a normal spine on the 

 left operculum, while that on the right operculum was directed ventrally at an angle of about sixty degrees 

 from the normal position. 



