FORM AND FINS 



face is accurately rounded, 

 and there appear no irregu- 

 lar points which could re- 

 tard the forward motion of 

 the fish. Even in the 

 wedge-shaped head the 

 conical surface has been 

 made more perfect by the 

 tightly fitting rims of the 

 jaws, by the smoothly 

 closed gill shields, and by 

 the eyes' accurate adjust- 

 ment to the head's curva- 

 ture. Viewed from in front 

 (Fig. 4) the fish's outline 

 appears as a perfect ellipse, 

 and seems surprisingly 

 small in size : the fins, which 

 appear so prominent a feat- 

 ure in profile, can now 

 be hardly distinguished ; 

 above and below they form 

 keels, sharp and thin. In 

 side view the vertical or 

 unpaired fins are seen sur- 

 rounding the hinder region 

 of the body : they resolve 

 themselves into dorsal {D), 

 anal {A), and caudal (C) 

 elements ; the former are 

 low and stout, elastic in _,. ^ ^ -^ • • . u 



Fig. 3. — Type of swift swimming fish, 

 their firm cutwater margin, Spanish mackerel, Scomberomoriis iiiacula- 

 A^^^^. 4. 1- 1 1 • . /^^J- (Mitch.), J. &G. X i. (After GOODE 



deeply notched and mter- in u. s. f. c.) 



