302 Field Museum of Natural History — Zoology, Vol. VII. 



ff. Body naked or variously armed with prickles or bony plates. 



CottidcB, 335 



ee. Chin with a barbel; dorsal and anal fins with more than 30 



rays; caudal fin isocercal. Gadidce, 338 



Family Oa^terosteidse. 



The Sticklebacks. 

 Body fusiform tapering to a slender caudal peduncle; skin naked 

 or with bony plates; middle and sides of belly shielded by the pubic 

 bones; mouth large, the cleft oblique; jaws with villiform teeth; 

 dorsal fins with the spines not connected by a membrane; ventrals 

 abdominal, composed of a stout spine and a rudimentary ray; pyloric 

 coeca few in number; air bladder simple. 



a. Dorsal spines 4 or 5, in a straight line; tail deeper than broad, 



without keel. Eucalia, 302 



aa. Dorsal spines 8 to 1 1 , not in a straight line ; tail not deeper than 



broad, with a lateral keel. Pygosteus, 303 



Genus Eucalia Jordan. 

 Body elongate, fusiform; skin without bony plates, dorsal spines 

 6 or fewer, in a straight line; tail deeper than broad, and without keel ; 

 pubic bones united forming a lanceolate plate with a single strong 

 median keel. 



Eucalia inconstans (Kirtland). Brook Stickleback. 



Head 3.2 to 3.8; depth 3.8 to 4.4; D. iv to vi, 9 or 10; A. i, 9 

 or 10. 



Body elongate, moderately compressed; caudal peduncle not 

 keeled ; mouth small and very oblique, the maxillary not reaching the 



Fio. 67. Brook Stickleback. 



Eucalia incontUtM (Kirtlaml). (After Forbux iiml Uichunlson.) 



