60 



Family Vlll. ATHERINID^. (The Silversides.) 

 Genus 23. Labidesthes, Cope. 



46. Labidesthes sicculus, Cope. — Brook Silverside. 



A very abundant minnow in small streams and lakes in central and north- 

 ern Illinois; also occuis rarely in the Wabash Valley, commonly in Rock 

 river, and occasionally in the Illinois 



Order II. HEMIBRANCHII. 



Family IX. GASTEROSTEID.E. (The Sticklebacks.) 



Genus 24. Gasterosteus, L. 



47. Gasterosteus inconstans, Kirt. — Brook Stickleback. 



Locally common in rivers and small streams in the northern part of the 

 State only. We have not taken it south of Rock river. 



Sub-class PHYSOSTOMI. 



Order III. APODES. 



The Eels. 



Family X. Anguillid^. (The True Eels.) 



Genus 25. Anguilla, Thunberg. 



48. Anguilla rostrata, Le Sueur. — Common Eel. 



Not very abundant, but occurring everywhere in streams of large and mod- 

 erate size, throughout Illinois. 



Order IV. HAPLOMI. 



Family XI. ESOCID^. CThe Pikes.) 



Genus 26. Esox, L. 



49. Esox nobilior, Thomas.— Muskallunge. 

 Found by us ®nly in Lake Michigan. 



50. Esex lucius, L. — Pike. 



Throughout the State, but most abundant northward. Occurs also in Lake 

 Michigan. 



51. Esox vermiculatus, Le Sueur. — Little Pickerel. 



(Bui. II, 53; Esox salmoneus, Esox cypho.) 



An abundant species north and south, occuring most commonly, perhaps, 

 in weedy lakes, but scarcely less frequently along weedy margins of rivers 

 and smaller streams. 



Family XII. UMBRID^. (The Mud Minnows.) 

 Genus 27. Umbra, Miiller. 



52. Umbra limi, Kirt.— MuD MiNNOW. 



(Bui II, 52; Melanura limi.) 



Lakes and muddy ponds in Northern and Southern Illinois; not taken by us 

 in the central part of the State. Occurs occasionally in running streams, as 

 in Fox river, at McHenry. 



