214 FISHES OF ILLINOIS 



ward across cheek and opercle and through eye to end of snout ; belly pinkish 

 white; median fins more or less specked with dusky, anal faintly so and only 

 near base; males with sides crossed by 16 or 17 rather obscure bars of dusky, 

 and with edges of lateral band somewhat serrate; anal with two or three rows 

 of prominent dark specks. Head much depressed and rather elongate, 3.5 to 

 3.9 in length; width of head 1.6 to 2; interorbital space 2.2 to 2.5; eye 3.3 to 

 3.9; nose 2.8 to 3.4, noticeably longer than eye; maxillary 2.8 to 3.3 in head, 

 mandible greater than eye; jaws subequal, the lower scarcely so long as 

 upper; " teeth in a broad band, the outer series considerably enlarged, 

 canine-like" (J. & E.). Dorsal inserted behind ventrals, its rays 9; anal rays 

 11, the fin noticeably longer in males (longer than head) than in females 

 (about V$ head); ventrals to vent; pectorals almost or quite to ventrals, 1.4 

 to 1.9 in head. Scales 33 to 34; transverse series 11; cheeks and opercles 

 and top of head covered with large scales. 



This is much the most abundant Illinois species of its 

 family, and is the one to which the name of top-minnow has 

 been most generally attached. It occurs in great abundance 

 throughout the state in waters of all descriptions, most fre- 

 quently, however, in the smaller streams and headwaters of 

 southern and eastern Illinois. Its condensation southward is 

 illustrated by our frequency coefficients for the three sections 

 of the state 2.13 for southern Illinois and .42 and .44 for 

 central and northern Illinois respectively. By far the greater 

 part of our collections have been taken from the basins of the 

 Kaskaskia and the Wabash, and the ponds and creeks of the 

 extreme southern part of the state. 



Outside Illinois it occurs from Michigan, and Wisconsin 

 southward throughout the entire lower Mississippi Valley to 

 Louisiana and the rivers of Texas. It is reported by collectors 

 to be most abundant in ponds, creeks, and canals, and along the 

 margins of sluggish streams. It is a surface swimmer, as its 

 common name implies, and, like Fundulus dispar, it is easily 

 distinguished in the water by a silvery occipital spot. 



Nearly the whole food of the species consists of insects, as 

 illustrated by our examination of 17 specimens taken from vari- 

 ous places in central and southern Illinois. The 10 per cent, of 

 vegetation eaten by these fishes was almost wholly filamentous 

 algae, taken in such quantities by some as to make it certain that 

 their presence in the food was not a matter of accident. In one 

 fish, for example, the entire intestine was crammed with these 

 algae, and in three others they made more than half the food. 

 Insects were the major part of the remainder, although Ento- 

 mostraca and amphipod Crustacea (Crangonyx) were likewise 

 common. 



