500 CONUEIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY — IV. 



line; a black spot at tlie base of the caudal; fins barred. Head 4; 

 depth 6. D. XV-15; A. II, 9; Lat. 1. 92. L. 6-8 inches. Great Lakes 

 and streams of the South and West; the largest of the darters. 



(ScicBna caprodes Rafiuesque, Amer. Month. Mag. 1818, 534: Pileoma semifascialum 

 DeKay, New York Fauna Fish. 1842, 16: Etheostoma caprodes, nebulosa, semifasciata, 

 and bimaculata Storer, Synop. Fisli. N. A. 270-272; Girard, Proc. Acad, Nat. Sci. Phila. 

 18o9, (36: Pileoma semifasciatum Giintlier, i, 76: Pileoma caprodes Vaillant 1. c. 4:i; 

 Jordan, Man. Vert. 220: Pileoma carionaria Baird & Girard, Proc. Acad. Nat. Sci. 

 Phila. 1853, 387: Pileoma carhonaria Giinther, i, 76: Pileoma carhonaria Girard, 1859, 

 10: Percina carhonaria Girard, Proc. Acad. Nat. Sci. Phila. 1859, 67; the latter a 

 variety from Texas with the fins mostly higher.) 



Var. manitou Jordan. 



Space in front of spinous dorsal naked; lateral bars short, more or 

 less confluent, each one not meeting its fellow of the other side across 

 the back; otherwise essentially as in the preceding, with which it inter- 

 grades. Chiefly northwestward; abundant in Wisconsin. Examples 

 intermediate between caprodes and manitou from Potomac Eiver {Bean; 

 Jouy) and Illinois {Forbes). 



{Percina manitou Jordan, Proc. Acad. Nat. Sci. Phila. 1877, 53.) 



261.— AtVORDIUS Girard. 

 Black-sided Darters. 



(Etheostoma Agassiz; not of Rafinesqne.) 

 (Girard, Proc. Acad. Nat. Sci. Phila. 1859, 68: type Alvordius maculatus Girard.) 



Body rather elongate, little compressed. Mouth rather wide, ter- 

 minal, the lower jaw included, the snout above not protruding beyond 

 the premaxillaries, which are not protractile. Teeth on vomer, and 

 usually on palatines also. Gill-membranes separate. Scales small, 

 ctenoid, covering the body. Belly with a median series of enlarged 

 spinous plates, which fall off, leaving a naked strip; sides of head 

 scaly or not. Lateral line complete. Fins large, the soft dorsal smaller 

 than the spinoiis or the anal. Anal spines 2; dorsal spines 10-15. 

 Vertebrse 22 + 22 {A. aspro); 17 + 22 {A. evides). Coloration bright; 

 sides with dark blotches. The most active and graceful of the darters. 



(Dedicated to Maj. B. Alvord, who discovered "Alvordius maculatus" at Fort Gratiot, 

 on Lake Huron.) 



a. Vertebrae more than 40; dorsal spines 11 to 15; palatine teeth present. (Alvor- 

 dius.) 

 b. Cheeks, opercles, and ante-dorsal region entirely scaleless; head very long and 



large; lat. 1. 75-80 macrocephalus. 



bb. Cheeks covered with fine scales; opercles with larger ones, 

 c. Head very slender, with long acuminate muzzle; jaws nearly equal; space be- 

 fore dorsal scaled; lat. 1. 65-70; lateral blotches small, quadrate. 



phoxocephalus. 

 cc. Head stouter, with wider muzzle; lower jaw included aspro, nevisenais. 



