THE REAKING OF SEA-FISH LARVAE. 89 



The object of the experiments being now achieved, I decided to 

 preserve the little fishes at this stage (three mouths old) in order to 

 have material for a detailed account of their development. 



The young fishes, even in the preserved condition, are attractive little 

 objects. Compared with young salmon or trout fry of the same length, 

 they are seen to be much more robust, partly owing to the shortness 

 and distension of the abdominal region. In the young trout the ventral 

 surface of the body from mouth to tail forms a practically straight line, 

 while the dorsal surface is evenly arched; in the young Blenny the 

 dorsal surface is straight, and the ventral is arched. The greatest 

 depth of the body in the young trout lies nearly midway between the 

 mouth and the base of the tail; in the Blenny it occurs immediately 

 behind the head. 



The skin is darkly pigmented with black chromatophores over the 

 front half of the body, but is still colourless and transparent in the 

 posterior part of the caudal postanal region. Behind the head the 

 dark brown pigment is distinctly arranged in a series of vertical bars. 

 A broad bar covers the front half of the abdominal region, and extends 

 over the anterior part of the first dorsal fin. After a narrow interval, 

 a narrower and more clearly defined bar extends across the hindmost 

 region of the abdomen at the boundary between it and the caudal 

 region. Corresponding with this bar, though slightly anterior to it, is 

 the black ocellus of the first dorsal fin, which extends between the 

 sixth and eighth fin-rays, and is well defined in the larger specimens, 

 though still undeveloped in the two smallest. From the ocellus to 

 the ventral margin of the body the bar follows a backwardly directed 

 curve, which becomes almost vertical below the region of the lateral 

 line. The alternating pigmented and unpigmented stripes are of about 

 equal width, equivalent to about the width of two adjacent interspaces 

 between the dorsal fin-rays. In the caudal (postanal) region, only one 

 of these bars is completely formed, but an additional one is distinctly 

 indicated in the largest specimens. The brown pigmentation of the 

 trunk thus extends backwards as growth proceeds, not as a continuous 

 sheet, but in the form of vertical stripes. 



Yellow and red chromatophores are also present, but are not easily 

 located. 



The pupil of the eye is black, without any suggestion of blue. The 

 iris has a golden basis, obscured to a large extent by black chromato- 

 phores. 



The pectoral and pelvic fins are covered with black chromatophores. 

 An interesting series of changes in the colour of the pectoral fins took 

 place during growth. In the newly hatched larva these organs were 

 black, as figured by Holt ; but about a week or ten days afterwards, if 



