706 The Development of Flounders. [ December, 
to have passed through the head between the frontal bone and 
the base of the anterior rays of the dorsal fin. As I had, however, 
followed the whole development in living specimens, I knew from 
actual observation that the mode of transfer of the right eye had 
been identical with that of the preceding species. These obser- 
vations thus far confirm in the main Malm’s explanation of the 
development of young symmetrical flounders into the well-known 
older stages. To my great astonishment, therefore, I captured 
one day a number of flounders (about an inch in length) closely 
allied to the Plagusie of Steenstrup, the so-called Bascania of 
Schiddte ; they were so perfectly transparent that they seemed 
the merest film on the bottom of the glass vessel in which they 
were kept. They were still entirely symmetrical, the eyes well 
removed from the snout, with a dorsal fin extending almost | 
to the nostril, far in advance of the anterior edge of the orbits | 
of the eyes. They were of course at once set down (from their 
size) as belonging to a species of flounder in which the eyes 
probably remained always symmetrical, and I prepared to watch 
its future development. It was therefore with considerable in- 
terest that I noticed, after a few days, that one eye, the right, 
moved its place somewhat towards the upper part of the body, 
- so that when the young fish was laid on its side, the upper half 
of the right eye could be plainly seen, through the perfectly trans- 
parent body, to project above the left eye. The right eye (as 18 
the case with the eyes of all flounders), being capable of very eX 
tensive vertical movements, through an are of nearly 180°, could 
thus readily turn to look through the body, above the left eye, 
- see what was passing on the left side, the right eye being of course . 
useless on its own side as long as the fish lay on its side. I may 
mention here that this young flounder, until long after the right eye 
came out on the left side, continued frequently to swim vertically, 
and that for a considerable length of time. This slight upward 
tendency of the right eye was continued in connection with a 
motion of translation towards the anterior part of the head till 
the eye, when seen through the body from the left side, was en- 
tirely clear of the left eye, and was thus placed somewhat in ad- 
vance and above it, but still entirely in the rear of the base of the 
dorsal fin extending to the end of the snout. What was mY - 
tonishment on the following day, on turning over the young 
flounder on its left side, to find that the right eye had actually 
sunk into the tissues of the head, penetrating into the space be- 
tween the base of the dorsal fin and the frontal bone, to such a" 
and 
RTE EAT. T aT Ne Ome OR AE Roemer tps 
