810 PROFESSOR W. C. M'INTOSH AND MR E. E. PRINCE ON 



the dorsal line of the abdomen, and a linear series also passed along the ventral line of 

 the body posteriorly. These tiny, though active and vigorous, forms, had already left the 

 surface where their early larval life is spent, and consorted with their older brethren 

 in the still water of the open sea at 25 fathoms. The next stage, as shown in these spirit- 

 preparations, is about 7'5 mm. long, and the chief changes noted are as follow : — The size 

 of the head has further increased, and the snout is longer ; moreover, several sharp spinous 

 processes project from the occipital area, though those on the operculum are not yet much 

 developed. The translucency of the head permits the brain to be fairly seen, and the 

 nasal organs are clearly outlined, as well as the facial and branchial cartilages. The 

 pectorals form large fan-like organs with pigment-corpuscles thinly sprinkled towards the 

 tip. The rays (thirteen in number) are all united by membrane, so that the three 

 filaments which are free in the adult must be separated later. While the proportions of 

 this anterior pair of fins are great, the upper rays being nearly half the length of the 

 body, the ventral fins project as mere buds, so that their use in progression is trifling 

 when compared with the same organs in such a form as the young ling (see p. 829). 

 Along the ventral margin at the tip of the notochord, which is not yet bent upward, 

 three hypural elements are visible, the first being large and prominent, the last merely a 

 thin band below the termination of the chorda. Cartilaginous rays now appear in the 

 ventral division of the caudal, but are absent in the median and upper portions of the 

 fin, in which embryonic fin-rays still occur. In the next stage, one or two millimetres 

 longer (i.e., 8 mm. or 9 mm.), the hypural elements have assumed a broad wedge-shape — 

 with an even edge posteriorly and slanting from above downward and forward. Only 

 a short process of the notochord is free, and this part is slightly flexed upward. The 

 marginal fin still continues from the dorsum to the tail, and the inferior lobe of the latter, 

 with its cartilaginous rays, has increased so as to constitute its greater part ; while the 

 upper lobe, with its embryonic fin-rays, has decreased in size. The great pectorals seem 

 to be growing, while the ventrals are also larger, and their rays are variegated with 

 black pigment. Upon the head the spinous processes are more distinct. 



When the young gurnard has reached the length of 10 mm., spines not only appear 

 on the operculum, the angle of the jaw, and the facial surface, but attain some size, two 

 upon the occiput being especially prominent. The long upper rays of the wing-like 

 pectorals reach nearly half the length of the fish, while the ventrals show considerable 

 growth, and project freely as small fins thickly pigmented with black corpuscles. Their 

 length is not quite equal to that of the basal part of the pectorals, which are, compara- 

 tively speaking, enormous. The posterior border of the hypurals is nearly straight (in a 

 vertical direction), and the free portion of the tip of the notochord has diminished. The 

 small upper lobe of the tail continues to decrease, though the delicate embryonic rays are 

 still visible in it. The remnant of the marginal fin fringing the trunk shows no carti- 

 laginous rays. 



When 15 mm. long, specimens present much the same features as the last stage 

 (PI. XVII. fig. 5), but the nuchal spines upon the occiput are characteristically promi- 



