PISCES 



The Structures of the Yellow Perch, 

 Perca fiavescens 



I. External features : 



(a). Form of body — Comj5are with the stone cat and the 

 porgy. Compare the skin of the catfish and perch. 

 Restilt? 



(b). Lateral Hne — (For this study use the common white 

 sucker.) A line on the side of the body extending 

 from the head to the tail. Examine with a lens. Of 

 what is this line composed? Trace the lateral line 

 upon the head of the pike or a pickerel. 



(c). Mouth — Is it terminal, superior, or inferior? Examine 

 the mouth of a white sucker and of a stargazer. 

 Which jof the above terms applies ? 



(d). Barbels — Examine a catfish and the creek chub. The 

 barbels aire fleshy projections about the mouth. 

 Does the perch possess such structures ? 



(e) . Operculum — ^A flap on the side of the head covering the 

 gills. Lift its caudal free margin to expose the gUls. 



(f). Branchiostegals and branchiostegal (or giU) membranes 

 — Turn the specimen upon its back. Extending 

 ventrad from the operculum is a membrane sup- 

 ported by curved rays. The membrane is the 

 branchiostegal or gill membrane, and the rays are the 

 branchiostegals. Determine their number. Write 

 the formula. 



(g). Isthmus — ^A narrow strip on the ventral side of the 

 head, extending from the chin' to the breast region. 

 Are the giU membranes joined to it? Examine the 

 white sucker. Result? Make a diagram of this 

 ■region in the perch and in the sucker. Examine this re- 

 gion in the bowfin, Amiatus, and note the ovoid gular 

 plate between the rami of the lower jaw. Draw. 

 ,(h). Fins. 



(i). Names, ntmiber and position. 

 (-2). Types of tails. 



(a). Heterocercal — Study ahddraw tail of 

 the gar. 



