BOLEOSOMA TESSELLATED DARTERS 299 



B. nigrum, but paler, the side markings less distinctly W-, X- and 

 V-shaped; color pattern of upper portion of body and back more open 

 being less densely and finely tessellated than in the preceding species'; 

 back with S or 6 saddle-like blotches, the corners of which are more 

 or less distinctly connected by dark markings, giving the fish the appear- 

 ance of being marked dorsally with a chain of rings, which are dark or 

 light according as the eyes are focused on the saddle-like dark blotches 

 and their connecting bands, or on the circular light areas intervening; 

 an evident dark spot on opercles; a conspicuous zigzag streak on nose 

 in front of eye and a very faint suborbital bar; dorsals and caudal faintly 

 barred. Head 3.9 to 4.3, slightly shorter and considerably narrower 

 than m B. nigrum, its greatest width 2 to 2 . 5 in its length; interorbital 

 space flat, 5 . 2 to 6 . 6 in head ; eye.round, 3 . 3 to 4 in head, not protruding 

 above the cranium ; nose bluntly rounded, less decurved than in B. nigrum, 

 3 . 8 to 4 . 5 ; mouth rather small, maxillary to front of pupil, cleft 3 . 1 to 

 3 . 8 in head ; lower jaw included ; gill-membranes not broadly connected, 

 .distances to angle and to back of orbit equal. Dorsal fin VIII-X, 10 or 

 11 (usually IX-10); spinous and soft portions well apart, separated by 

 a distance about equal to diameter of eye; height of first dorsal 1 . 7 to 

 1.9 in head, second 1.4 to 1.7 (height of first 70 to 90 per cent, of 

 second); caudal slightly emarginate; anal I, 7.-or8; pectorals 1 to 1.3; 

 separation of ventrals as a rule considerably less than their width at 

 base. Scales 6, 52-60, 6 or 7 [7-10]; lateral line ordinarily developed on 

 only about half the scales; cheeks, opercles, andhreast fully scaled; nape 

 with a median naked strip ; belly covered with ordinary scales. 



This rather insignificant but interesting little darter is one of the 

 more distinctly southern species of the group. Although it has been 

 taken by us in Illinois as far north as South Chicago on the east 

 and Green River, in Henry county, on the west, our southern Illinois 

 collections preponderate greatly in number over those of central or 

 northern Illinois, the relative frequencies being 2.44, .46, and .10 

 for these three sections of the state. Like its nearest relative, the 

 Johnny darter, it is essentially a species of creeks and the smaller 

 rivers, if we may judge by our 107 collections; but it is found more 

 frequently than that species in standing water, especially in the 

 lakes and ponds of the river bottoms, and much more frequently 

 also in rivers of the largest class — thirty times, for example, from 

 Havana and Meredosia, where Boleosoma nigrum was obtained but 

 twice. It is most abundant in the Big Muddy and the Saline River 

 basins, occurring in the first in seven out of nine collections, and in 

 the second in eleven out of eighteen. It is especially peculiar in the 

 fact that more than two thirds of our material was taken from quiet 

 waters, and about three fifths of it from waters with a muddy bot- 

 tom. In geographical and local distribution and in ecological pref- 

 erence, this little species thus separates itself notably from its nearest 

 ally. 



