BY THE PRESIDENT. 
117 
In the monkfish the common skin of the body passes oyer the 
eye, and has the function of an eyelid. The eyes of the skates or 
rays are particularly worthy of notice. Hanging from the upper 
part of the iris is a fringed curtain which nearly covers the pupil. 
It is generally supposed that this organ is used for shutting off the 
light when too brilliant. This may certainly be of service to flat 
fishes like the skates whose eyes are more exposed to the direct 
rays of the sun. But another suggestion has been made, viz. that 
the fimbriated veil may serve to limit the retinal image to the 
object looked at, and thus prevent the attention of the fish from 
being unnecessarily diverted. Should this be the case, the curtain 
of the eye of skates is analogous to one of the means used by 
photographers to produce a vignette. In contradistinction to the 
rays, the flat fishes ( Pleuronectidce ), such as the sole and plaice, are 
remarkable for their asymmetrical bodies and the position of their 
eyes. At an early stage their form is symmetrical, and their eyes 
are on opposite sides of the head, like those of an ordinary fish.* 
The depth of their bodies, the small size of their lateral fins, and 
the absence of a swimming-bladder, render difficult the maintenance 
of a vertical position. Falling on one side, they try to see above 
them with the lower eye, and their efforts are so constant that 
the bones of the head become contracted and their eyes acquire the 
well-known abnormal position. 
The sense of sight has possibly been more elicited by man in the 
fresh-water fish than in any other group of animals. The nature 
of their habitat and the etiquette of sport require that they should 
be captured by wiles which may be detected by acute sight, and 
where angling is constant the fish soon learn to distinguish between 
their food and the bait. It is true, deep-sea fish are caught with 
clumsy tackle, but that may be partly due to the few individuals 
which have, out of an untold number, had the opportunity to gain 
experience of a hook. The visual judgments of fish and the art 
of the angler are, in a much-frequented stream, running a race. 
Wit sharpens wit. The dry fly has become a necessity where the 
trout are accustomed to the appearance of a sunken fly, and anglers 
* See. Traquair “ On the Asymmetry of the Pleuronectidse,” ‘Trans. Linnean 
Soc.,’ vol. xxv, p. 263. Van Beneden in 1853 (“ Note sur la Symetrie des Poissons 
Pleiironectes dans le jeune age,” ‘Ann. des Sciences Naturelle,’ 3e serie,vol. xx, 
p. 340) first recorded the change of position of the eyes of the Pleuronectidae. 
A. W. Malm also elucidated the true mode in which the eye passes from the 
blind side (‘ Svensk. Yet. Akad. Handl,’ vol. vii, 1868, p. 28). A translation 
of Schiodte’s paper “ On the Development of the position of the Eye in Pleuro- 
nectidae ” is in ‘ Annals and Magazine of Natural History,’ ser. 4, vol. i, p. 378. 
Steenstrup in 1863 (‘ Of vers. Dansk. Yidensk. Selsk. Forhandlung.’ 1863, p. 145), 
stated in error that the eye of the blind side pierced the tissues of the head to 
reach the other side. 
