DEVELOPMENT AND LIFE-HISTORIES OF TELEOSTEAN FISHES. 841 



ordinary views the body appears to be almost linear. A peculiar feature is the presence 

 of minute dark pigment-specks on the ventral lobe of the marginal fin, whereas into the 

 dorsal lobe (ef) only one or two of the yellowish corpuscles pass from the line of the 

 body. In this early stage the otoliths are remarkably small — much less, for instance, 

 than in the fluke of the same age. The larva swims actively at the surface of the 

 water, and is not easily noticed except by its large iridescent eyes, which now and 

 then exhibit a golden sheen. Like some other young forms already described, it floats 

 head downward in the water, besides frequently boring its snout into the sand at the 

 bottom of the vessel. When at rest it lies upon its side at the bottom, and if the 

 background be dark the yellowish pigment is conspicuous, especially in the caudal 

 region. A perceptible increase in length took place within a few days after emer- 

 gence. There is so little difficulty in hatching these ova, that this species could be 

 multiplied in any suitable locality which it did not already inhabit. Mr Cunningham # 

 describes the yellowish spots as being in three rows on the lateral region of the embryonic 

 plaice. 



In April large numbers of young pleuronectids at and near 12 mm. in length occur in 

 St Andrews Bay. The eyes in these are generally asymmetrical, though in the smallest 

 forms very slightly so. In the most advanced the left eye projects above the dorsal ridge, 

 but is mainly used for vision on its own side. The blackish pigment-corpuscles are chiefly 

 developed along the ventral margin of the body, though in some the sides posteriorly, 

 and the posterior half of the dorsal margin, have a few specks. The terminal region of 

 the notochord varies from a long dorsal filament to a mere trace beyond the hypural 

 elements in the older examples. 



The foregoing may represent both the young of the plaice and the common flounder, 

 the earlier post-larval stages in spirit not yet having been clearly separated. 



At the mouth of the Thames, young plaice 1^ inch and upwards abound in the nets 

 of the shrimpers in October, and similar forms are met with at a later period at the 

 margin of the sandy beach at St Andrews. In June and July, at the latter place, the 

 smaller forms range from 2^ to 3^ inches, and these are probably the young of the 

 previous season. It is a noteworthy feature in connection with this and other species, 

 that tlje larger forms are characteristic of the deeper water, while the smaller, from 1 1 

 inches downward, abound in sandy bays (inshore water). The mature fishes (i.e., those 

 with the reproductive organs fully developed), as formerly shown, are thus mostly beyond 

 the three-mile limit. 



Pleuronectes jlesus, L. — No form is better adapted for studying the development of 

 pelagic Teleostean ova than this, though, as one of us has elsewhere pointed out, 

 specimens in confinement seldom deposit healthy ova.t The comparatively rapid 

 development of the embryo (six to seven days) is further favourable for a connected 

 series of observations, The lateness of the spawning period in 1886 was also fitted to 



* Op. cit., p. 99. 



+ Vide account of appearance of retained ova, Third Annual Report of Scottish Fishery Board, 1885, p. 62. 

 VOL. XXXV. PART III. (NO. I9). 6 P 



