28 1 4 THE BONY FISHES AND GANOIDS 



induced to leave the bottom long enough to enable me to see whether it holds itself 

 perfectly horizontal or not. I have never seen it leave the bottom of its own accord; 

 it lies always buried in the sand up to its eyes, and, when disturbed, makes violent 

 struggles to bury itself again." 



When lying on the sandy bottom of the sea and they prefer sandy to muddy 

 situations flatfish are almost indistinguishable from their inanimate surround- 

 ings, the spots with which the bodies of many of them are marked harmonizing ex- 

 actly with the bright-colored pebbles strewing the sand. This resemblance is, 

 perhaps, carried to the fullest extent in the flounder, as anyone who visits a large 

 aquarium may ascertain for himself. Occasionally rising to the surface, they swim 

 with an undulating lateral movement of the body, which is decidedly graceful; and 

 they are found in shallow water, or at moderate depths. They are inhabitants of 

 all seas, except those of the polar regions, and where the coast is precipitous and 

 rocky; and although more numerous in the tropics, they attain their greatest devel- 

 opment in point of size in the temperate regions. Many species, such as flounders, 

 ascend rivers to a considerable distance; and a few have become accustomed to a 

 fresh-water existence. As regards food, the whole of the species are exclusively 

 carnivorous. In the fossil state the flatfish are but poorly represented, and it is 

 probable that they were not evolved till the commencement of the Tertiary period; 

 the earliest known forms being a turbot from the middle Eocene of Monte Bolca, 

 while a fossil sole has been described from the Miocene of Wiirtemberg. As a food 

 supply the flatfish are of especial value, not only on account of the large size, and 

 abundance of their numerous representatives, but likewise from the excellent 

 quality and flavor of the flesh of the majority of these. It is on the coasts of the 

 temperate regions of the Northern Hemisphere that the pursuit of these fish is car- 

 ried out with the greatest energy and success. 



The least specialized member of the family (Psettodes erumei}. which 

 Psettodes 



ranges from the Red Sea through the Indian Ocean to China, and also 



occurs on the west coast of Africa, belongs to a group in which the teeth and jaws 

 are nearly equally developed on both sides, and is specially distinguished by the 

 dorsal fin commencing on the nape of the neck, whereas in all the other forms it starts 

 from above or in front of the eyes. In the Indian fish, which attains a length of 

 about sixteen inches, the eyes are as frequently on the right side as on the left side, 

 and the transposed one is situated nearly in the line of the dorsal fin. This species 

 is a connecting link between the other members of the family and ordinary fishes, 

 and is reported to swim at times in a vertical position. 



Having the jaws nearly equally developed on both sides, and the 

 dorsal fin commencing above the eyes, the holibut (Hippoglossus vul- 

 garis) is one of two species forming a genus characterized by the eyes being on the 

 right side, and the teeth of the upper jaw arranged in a double series, those in the 

 front of the upper and on the lower jaw being enlarged. The mouth is relatively 

 wide. In color the holibut is dusky brown, frequently inclining to olive, on the 

 dark side; the opposite side being white and smooth. It is the largest member of 

 the family, ranging usually from three to six feet in length; one specimen with the 

 latter length having a breadth of thirty inches, and a weight of one hundred and 



