CAMPOSTOMA — STONE-ROLLERS 111 



surface; nose 2.3 to 2.S, the muzzle moderately decurved, overhanging the 

 rather large :m<l horizontal mouth; maxillary 3.3 to 4.6 in head, reaching 

 scarcely back of vertical from posterior nostril; lower jaw wholly included; 

 upper lip quite fleshy; breadth of isthmus 1.3 to 1.5 times diameter of orbit. 

 Teeth 4-4 or 1,4-4,0, with oblique grinding surface without terminal hooks, 

 or with only a slight one on one or two teeth; intestine 5 to 9.5 times length 

 of head and body; peritoneum black. Dorsal fin with 8 rays, set slightly 

 behind ventrals and nearly midway between muzzle and base of caudal; 

 longest dorsal ray 1.2 to 1.6 in head; anal rays 7; pectorals about % to 

 ventral?, 1.2 to 1.4 in head, ventrals falling quite short of vent in males, 

 reaching or almost reaching it in females. Scales rather small, 6-8, 46-53, 

 6-8, more or less crowded forward, the crowding scarcely noticeable in females 

 but very evident and often conspicuous in old males; scales on breast very 

 small, about 15 transverse series between pectorals; scales before dorsal 15 

 to 26; lateral line complete. 



This is a species of wide distribution occurring in the Great 

 Lake region, along the south Atlantic slope to the Gulf, and in 

 the valley of the Mississippi from Wyoming to Indiana, Ohio, 

 and Texas. 



It is a fish of the creeks and the smaller rivers, its ratios of 

 preference, according to our collections, being 334 f° r the former 

 and 234 for the latter. It has been taken only occasionally by 

 us from rivers of a large size, and but rarely from lakes and ponds. 

 Indeed, the notable preference of the species for rocky or sandy 

 streams as shown by its frequency coefficient of 3.26, and for 

 swift water over still water (coefficients respectively, 1.70 and 

 .59) would tend to exclude it from stagnant or muddy waters of 

 any description. In accordance with these preferences, it has 

 not once occurred in our collections from the streams of the 

 lower Illinoisan glaciation, none of our 166 Illinois localities for 

 this species falling within that district. Nine of them are from 

 the hill region of extreme southern Illinois, and one is from the 

 Wabash in~ Wabash county, but the southernmost points for the 

 remaining 156 localities are in Montgomery county in the west- 

 ern part of the state, and in Coles county in the eastern part. 



This species is distinguished from all our other minnows by 

 the great length of the intestine, which is wound spirally about 

 the air-bladder. There are about twenty gill-rakers to each gill, 

 but they are so short as to constitute a very inefficient straining 

 apparatus. The pharyngeal teeth have well-developed grinding 

 surfaces, and are practically without terminal hook. Intestines 

 of specimens examined with reference to the food of the species 

 were invariably found filled from end to end with a slime-like 

 matter consisting almost wholly of fine mud from which, with 



