EXPLA.NATION OF PLA.TE. 



Fig. I. The Common Perch. {Perca flavescens.) 

 A. Anal fin. 

 C. Caudal fin. 

 I. Op. Interopercle. 

 M. Maxillary. 

 Op. Opercle. 

 P. Pectoral fin. 

 P. M. Premaxillary. 

 P. Op. Preopercle. 

 P. Orb. Preorbital. 

 S. D. Spinous dorsal fin. 

 Sfd. D. Soft dorsal fin. 

 S. Op. Subopercle. 

 V. Ventral fin. 



Fig. II. Head of a Calico Bass. {Pomnxis spavokles.) 

 S. M. Supplemental maxillary bone. 



Fig. III. Common Red Horse Sucker. {Moxostomi aureolum.) 

 Isth. Isthmus. 

 G. U. Gill membranes united to the isthmus. 



Fig. IV. The Common Perch dissected so as to show some of the internal organs. 

 A. B. Air-bladder. 

 G. Gills. 

 G. R. Gill-rakers. 

 I. Intestine. 

 P. C. Three pyloric cjEca. 

 S. Stomach. 

 U. B. Urinary bladder. 



