10 Fishery Board for Scotland. 



to such a depressed form as the adult Lcphius piscatorius. The larva is deeper than 

 broad, and the head, body, and tail are in the same line. The eyes are placed 

 laterally on the head, and the broad embryonic fin which borders the tail is continued 

 dorsally to the elements of the first dorsal fin. 



Agassiz and Whitman (1885) have described very minutely the development 

 of the larval forms until the completion of the absorption of the yolk, and Prince 

 (1890), in liis descriptions of Scottish specimens at the same stages of development, 

 has pointed out that they differ in some respects from the American forms. 



In the Scottish specimens hatched from isolated eggs, the first ray has not 

 appeared when the larva is newly hatched, whereas the American workers describe 

 the newly-hatched larva as possessing a single (first) dorsal appendage. As has 

 been pointed out already, the newly-hatched larva may be held for some time in 

 the gelatinous mass. There is the greatest difference, however, between the 

 American and North Sea specimens in the degree of development of black pigment, 

 especially on the tail. In the American specimens, there are three or four prominent 

 patches of intense black pigment placed at equal intervals along the lower, upper, 

 and terminal parts of the notochord. The tail pigment spots extend on both sides 

 of the notochord, and form the largest of the three patches. This is the case from 

 the earliest stages. On the other hand, in the Scottish specimens, the black 

 pigment is confined entirely to the head and anterior body portion of the larva. 

 Only very rarely is pigment found on the tail portion, and then only in the form 

 of single chromatophores. One chromatophore may sometimes be found at the 

 tail-tip on the notochord and another on the notochord in the middle of the tail. 



Variation in the intensity of development of the larval pigmentation is not 

 unusual in other species. Schmidt has shown that Gadoid larvse of the North Sea 

 are characterised by weak pigment development. 



Post-Larval Form with Three well-developed First Dorsal Rays and 

 Beginning of Second Dorsal and Anal Fins. 



{Fig. 6). 



The next stage illustrated is that of a specimen caught 30 miles E. of 

 Bard Head (60° 15' N.; 0° 7' W.) on 13th July 1905, in a depth of 125 metres. 

 The specimen had been some considerable time in formalin, and its length when 

 examined was 10 mm. Its actual length, when alive, would probably have been 

 slightly over 11 mm. Even in this preserved specimen the colour had not entirely 

 disappeared. The eyes retain their dark colour, and pigment still covers the head 

 and body, but it is not so dark as in the preceding stage. 



This stage may be indicated by the appearance of the elements of the second 

 dorsal and anal fins in the tail region. The rudiments of these fins are seen to arise 

 on the dorsal and ventral sides of the notochord in the still complete embryonic 

 fin which borders the whole tail region. As yet, however, there are no indications 

 of the first elements of the caudal fin, for the notochord is straight and the tail 

 pointed . 



Most of the specimens in the present collection are at this stage of development. 



The head and body region shows the first signs of that progressive change which 

 gradually leads up to the typical form of the adult. The head and body region 

 is now slightly more than two-sevenths of the total length, and placed at a somewhat 

 obtuse angle to the straight tail. There is no sign of flattening of the larva, however, 

 although now the eye has a relatively higher position on the head. It lies im- 

 mediately over the angle of the mouth. The bones of the mouth are well-developed. 

 The under jaw is very prominent, projecting beyond the upper, and is toothless. 

 The operculum is distinct behind the eye. The fin-rays of the first dorsal fin, 

 the pectoral and pelvic fins, show considerable advances in development from the 

 preceding stage. There are three well-developed fin-ray elements of the first dorsal, 

 and a fourth has made its ajjpearance posteriorly. The three anterior rays end in 

 fine filaments and are very long, exceeding the depth of the body. The first ray 

 h still th" longest. It arises directly over the cerebrum, and its jointed nature is 

 easily made out. Its real attachment is much further back. 



The pectoral fins have increased in size and are large, fan-shaped organs inserted 



