184 
FIFTEEN-SPINE D 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 shaip 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 C^s indeed, in many other fishes) quickly 
chansrinsc 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. 
0— Eggs, natural ske. 
