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



Percopsis guttatus Agassiz. Trout Perch. 



Head 3.2 to 3.7; depth 3.9 to 4.5; D. i or 11. 9 to 11; A. i, 5 to 7 ; 

 scales 47 to 54. 



Body elongate; not much compressed; mouth rather small, sub- 

 inferior; maxillary not reaching orbit, its length 3.0 to 4.0 in head; 

 snout 2.4 to 3.0; eye 3.5 to 4.0; dorsal fin inserted much nearer tip 



Fig. 58. Trout Perch. 



Percopsis guttatus Agassiz. (After Jordan and Evermann.) 



of snout than base of caudal, nearly over ventrals; scales strongly 

 ctenoid; caudal fin deeply forked. 



Color pale olive-buff above; silvery below; scales faintly edged 

 with black; 8 to 12 black spots on sides above lateral line; a dusky 

 median lateral band. 



Length 6 inches. 



This species inhabits the larger streams and lakes from the Sas- 

 katchewan to Hudson Bay, Delaware, and Ohio River. 



Lake Michigan, Chicago, Illinois; Lake Michigan, Pine, Indiana. 



Family Atlieriiiidse. 



The Silversides. 



Body elongate, .somewhat compressed; scales usually cycloid; 

 head usually with scales; lateral line absent or imperfect; ventral 

 fins abdominal ; two dorsal fins, the imterior consisting of 3 to 8 slender 

 spines, the posterior of soft rays; anal fin with one weak spine; gill 

 membranes not connected, free from isthmus; teeth usually present 

 on jaws; no pyloric cu?ca; air bladder present. 



