998 FISHES — GASTEROSTEID^. 



Smooth-skinned Sticklebacks with the caudal keel undeveloped ; the dorsal spines in 

 small number and placed vertically in a right line ; the spines all unserrated ; ventral 

 plates coalesced into a narrow plate on the.median line between the ventral fins ; a dis- 

 tinct snbqnadrate post- pectoral plate ; caudal peduncle comparatively short and stout j 

 gill-membranes posteriorly free from the isthmus. 



Small fishes inhabiting the inland brooks and lakes of the Northern United States. 

 But one species is certainly known, running into two or three varieties. This group is 

 probably unworthy of generic distinction from Gasterosttus, from which it differs mainly 

 in its feeble spines, and lack of armature, and in the freedom of the glll-membranea 

 from the isthmus. 



164. EucALiA iNCONSTANs (Kirtland) Jordan. 



Brook Stickleback. 



Gaaterosteus inoonstans, Kirtland, Bost. Journ. Nat. Hist., 1839; Stoker, Synopsis, 1846. 



—Cope, Proc. Ac. Nat. So. Phila , 186. 

 Apeltis ineonstans, Jordan, Ind. Geol. Surv., 1874, 1875, 217. 

 Eucalia ineonstans, Jordan, Man. Vert, 1876, 248; Proc. Ac. Nat. Sc. Phila., 1877, 65; 



Man. Vert., Ed. 1, 1878, 259.— Nelson, Bull. Ills. Nat. Hist. Soc, 1876 —Jordan and 



CoPELAND, Check List, 1876. 

 Gasterosteus micropus, Cope, Proc. Ac. Nat. Sci. Phila,, 1864, 186. 



var. pygmcea. 



Gaaterosteus pygmcBue, Agassiz, Lake Superior, 1850. 



Euealia ineonstans yslt. pygmcea, Jordan, Man. Vert., 1876, 248; Proc. Ac. Nat. Sc. Phila,, 

 1877, 66.— Man. Vert., Ed, 2d, 1878, 209. 



var. cayuga, 



Eucalia ineonstans var. eayuga, Jordan, Mai^. Vert., Ed. Ist, 1876, 249; Proc. Ac. Nat. So. 

 Phila., 1877, 66; Man. Vert., Ed. 2d, 1878, 2ri9. 



Description — Males in spring jet black, tinged anteriorly with coppery red ; females 

 and young olivaceous, mottled and dotted with black ; body moderately elongate, little 

 compressed, the caudal peduncle comparatively stout, not keeled ; skin smooth, entirely 

 destitute of dermal plates, the skeletal plates covered by it ; innominate bones small, 

 lanceolate, covered by the skin ; area in front of pectorals small ; thoracic processes very 

 slender and widely separated, covered by skin ; gill membranes somewhat free from the 

 isthmus posteriorly ; gill rakers short ; dorsal spines low, stibequal, in a right line, those 

 in front lowest, a cartilaginous ridge along their base ; ventral spines short and sharp, 

 serrated ; head 3J ; depth 4 ; D. IV-I, 10 ; A. I, 10. Length 2i!- inches. 



Habitat, sluggish, grassy brooks, from central Ohio, northern Illinois and Kansas 

 northward ; very abundant in the tributaries of the Great Lakes. 



Habits. — This interesting little fish is very abundant in many streams 

 in the northern part of Ohio. It frequents small brooks, lurking among 

 the weeds and grass, ready to dart on any luckless minnow or insect that 

 attracts its notice. In the aquarium these Sticklebacks are excessively 



