74 THE FKESH-WATElt FISHES OF EUROPE. 



form of the body is moderately compressed, highest under the second dorsal 

 spine, with the height exceeding the length of the head, and between one- 

 third and one-fourth of the length of the fish. The head is about three 

 and a half times as long as the eye. The eyes are separated by two- 

 thirds of their diameter. The cleft of the mouth reaches under the nares. 

 The teeth are relatively large in both jaws, and pointed. The longest 

 axis of the fish runs through the middle of the cleft of the mouth, and 

 touches the edge of the pupil of the eye. The very broad sub-orbital 

 bone extends back to the angle of the pre-operculum, with which it is 

 closely united, and, like the anterior smaller elements in the sub-orbital 

 ring and the operculum, is finely striped. 



The profile rises in a regular arch from the margin of the mouth to the second 

 dorsal spine. The body is four times as high under the dorsal spine as at the tail. 



The pectoral fins are truncated, and extend back as far as the second dorsal 



Fig. 28. GASTEKOSTEUS ACULEATUS 



spine, which is nearly opposite to the ventral fin. The third, or short, dorsal 

 spine is farther removed from the first two than are these from each other. 

 The soft dorsal fin has its upper edge straight and inclined backward, because 

 the anterior rays are nearly three times as long as the short posterior rays. 

 The vent is opposite to the third dorsal spine, and therefore nearer to the 

 tail than to the snout. The anal fin resembles the soft dorsal, and reaches 

 equally far back, but has a shorter base, and is preceded by a short, broad 

 compressed spine. The spine of the ventral fin is rough, and furrowed down 

 its length ; the fin also possesses a soft curved ray, which often reaches as 

 far back as the three-cornered pelvic shield, and therefore below the third 

 dorsal spine. In front of its base the pelvis forms an upward forked shield, 

 which lies between the lateral shields, when they are present, and reaches to 

 half the height of the body. The caudal fin is vertically truncated, and has a 

 length of about one-eighth of the length of the fish. In front of the first 

 dorsal spine, and close behind the back of the head, there is a small spine 

 with its point turned backward, followed by two others with their points 

 directed forward, but concealed under the skin. All the fin rays, except those 

 of the pectoral fin, are bifurcate at the end. 



