184 



FIFTEEN-SPINED STICKLEBACK. 



liberty. The gill-covers with large plates; the membrane with 

 three rays. The body lengthened, growing slender as it 

 approaches the tail, and depressed. The lateral line raised into 

 a ridge of sharp overlapping plates, forty in number, but 

 probably liable to variation. The belly bordered with a 

 prominent bony rim; vent at the middle of the body. Dorsal 

 and anal fins rounded, at the beginning of the posterior half 

 of the body, and opposite each other. Between the head and 

 the dorsal fin is a row of fifteen spines, each of them edged 

 on the hinder part with a slight membrane. Pectoral fins 

 rather large, reaching backward to the tenth dorsal spine. 

 Ventrals opposite the extremity of the pectorals, placed apart, 

 with three rays, the first strong and hooked. A strong spine 

 before the anal fin. The tail wide and round. The colour 

 liable to vary; in some reddish brown on the back, first rays 

 of the dorsal fins, and tail; in others deep green; and in 

 some instances (as, indeed, in many other fishes) quickly 

 changing under the influence of terror. The cheeks and sides 

 are often golden yellow, lighter on the belly. Fin rays — 

 pectoral nine, ventral three, dorsal seven, anal eight, caudal 

 twelve. 



A. — Head of Fifteen-spined Stickleback. B. — Egg of ditto magnified. 



C. — Eggs natural size. 



