FISHES OF MSNNESOTA 51 



Order HEMIBRANCHII. 

 Family GASTEROSTEID^. The Sticklebacks. 



Body somewliat compressed; the portion before the caudal fin 

 (caudal peduncle), very small. Head of medium size; mouth moder- 

 ate, the lower jaw projecting beyond the upper; maxillary bent, 

 overlapping the premaxillary at the corner of the mouth; jaws set 

 with sharp, even teeth; upper jaw protractile. Body not covered 

 with true scales; dorsal fin preceded by several free spines; bran- 

 chiostegal rays 3; ventral fins each with a stout spine; pectoral 

 fins inserted far back. Air-bladder simple; a small number of 

 pyloric caeca present. 



Small camiverous fishes, represented in our state by two genera 

 and at least two species. 



KEY TO THE GENERA OF GASTEROSTEIDJl. 



A. Dorsal fin with 4 to 5 spines. Eucalla, 51 



AA. Dorsal fin with 9 to 11 spines PygOSteus, 52 



Genus EUCALIA Jordan. 

 Eucalla inconstans (Kirtland). Brook Stickleback. 



Color varying to black, under parts usually lighter; some red 

 on the anterior parts of the spring males. Body somewhat elon- 

 gate, moderately compressed; the portion before the caudal fin 

 very small; no scales. Gill membranes somewhat free posteriorly; 

 gill rakers short; a ridge or keel along the base of the taU. Head 

 contained in the length 3^ times. Depth 4. Dorsal fin with 4 or 5 

 free spines and 10 soft rays (IV-I, 10). Anal I, 10. Length 2^ 

 inches. 



A very common little fish. Specimens have been taken in the 

 streams of the Upper Mississippi (Nat. Hist. Surv., 1893); streams 

 in the vicinity of Mankato and the southwest (Cox, 1891-95); the 

 Upper Minnesota River and the Bed River of the North and tribu- 

 taries (Woolman, 1892, Report U. S. Fish Comm., 1893, p. 372). 

 Sucalia inconstans pygmaea (Agassiz). 



This variety is said to differ from the typical E. inconstmis in 

 having a shorter and deeper body and the dorsal fin with III or 

 IV-I, 6 rays. Anal I, 6. It was described from Lake Superior aa 

 Gasterosteus pygmceus Agassiz, Lake Superior, 314, 1850. There 

 is some doubt as to the validity of this variety, so the Nat. Hist. 

 Surv. desires very much to get a large series of specimens from the 

 Lake Superior region. 



