DEVELOPMENT AND LIFE-HISTORIES OF TELEOSTEAN FISHES. 851 



A feature of interest in several was the remarkable size of the optic lobes, which projected 

 dorsally so as to give the head a " hooded " aspect, as in the condition before mentioned. 

 The agility of the little larva is characteristic. 



Three days later the activity of the larval fish had become even more marked, and it 

 seemed in a state of perpetual movement, the only interval being for a second or two 

 after a long course through the vessel. This almost ceaseless movement is probably 

 connected with respiration, the now widely open mouth being driven against the water 

 which thus rushes into it. The pectorals vibrate like those of Hippocampus (a re- 

 semblance the more appropriate from the dermal process on the vertex), and the tail 

 appears to move as rapidly. The larval soles chiefly kept the bottom of the vessel at 

 this stage, swimming obliquely with the head directed downward, as if boring into the 

 bottom or sides. Occasionally, however, a swift dart was made right across the vessel, 

 or a shorter one as if capturing prey. The mandible moves rapidly as in respiration. 

 The yolk has now diminished to a small mass anteriorly — with the groups of oil-globules 

 crowded together, while the posterior region of the abdomen is occupied by the viscera. 

 This forward progress of the yolk is interesting, for while different conditions occur in 

 different groups, one of the most common is the absorption of the anterior region, 

 and the consequent presence of the diminished yolk posteriorly. Another feature 

 of note is the occurrence of a prominent fold along the ventral margin of the abdomen. 

 The pigment seems in some to be more ochreous, and to have less of the dull yellowish- 

 white (like Tripoli powder) so characteristic of the early condition. Along the dorsal 

 margin of the muscle-plates are a series of pigment-patches, which appear to be more 

 numerous than in the example of the post-larval stage elsewhere described,* but variations 

 may occur in this respect. 



As the larval sole gets a little older, for instance two days subsequent to the preceding 

 stage, the pigment becomes more distinctly ochreous, and the yellow chromatophores 

 along the dorsal edge of the muscle-plates show signs of increase. Moreover, the pigment- 

 spot on the occiput so characteristic of the subsequent stage is outlined. Eight distinct 

 pigment-patches occur behind the former, one of the posterior (seventh from the occipital) 

 being larger and almost meeting that from the inferior edge. The character of the head 

 is as peculiar as in the previous stage, and the eyes are directed more or less forward 

 .(forward and outward), so that the active little fish can readily see in front. The yolk 

 has now shrunk to a small mass under the liver — in front of the gall-bladder, and is not 

 easily distinguished. The change from the buff or stone-coloured, or even the dull 

 yellowish-white, of the early stage, to the ochreous tint of the present one is a feature of 

 interest. Moreover, one of the most marked changes is the disappearance of the yellowish- 

 white pigment from the edge of the marginal fin, so conspicuous in the early larva, and 

 which renders it so easily observed in a glass vessel. The speckled condition may be 

 associated with the more helpless stage, when, perhaps, it frequently rests on the 



* Vide Ann. Nat. Hist, Dec. 1888, p. 469, and Seventh Annual Report, Fishery Board for Scotland, 1889, where a 

 coloured figure is given. ■ : 



