FLOUNDER-FISHES. 
March, the season which in the Southern Hemisphere 
corresponds to our autumn; but according to Risso", 
the Great Flying-fish of the Mediterranean has its 
ovaries full in spring. 
Exocoetus volitans is a rare species even on the 
west coast of France, though even there it has long 
been known, as in his time Duhamel'' received a spe- 
cimen 43 cm. long, from the English Channel. On the 
south coast of Ireland and in the Bristol Channel it has 
been observed somewhat oftener, even in shoals. It is 
said to have been taken once in the Irish Sea, north 
361 
of the Isle of Man; but it can scarcely be stated to 
occur further north on the coast of Great Britain. Still, 
a specimen about 32 cm. long, according to EsmariG, 
was caught “in a net off Moss at the head of Christiania 
Fjord, about 1850.' The specimen is preserved in 
Christiania Museum, but is somewhat damaged. Lutken, 
who was enabled to make a careful examination of this 
specimen, fixes its species as most closely approximating 
to Exocoetus bahiensis, though tie is unable to refer it with 
certainty to any of the species yet described. Lilljeborg 
unhesitatingly refers it to Exocoetus volitans ( exsiliens ). 
HETEROSOMATA . 
Malacopterygian Eleutherognates in which at least the o. 
state, with both eyes set on 
“Scarcely any other animal form,’ wrote Sundevall 
in the first edition of this work, “is so sharply defined 
by its characters and external appearance as the Flat- 
fishes . . . They are characterized by their broad, strongly 
compressed body, with the dorsal and anal fins occu- 
pying almost its whole length, and especially by the 
fact that both eyes are set on the same side of the 
head. The skull is so twisted that the eye on one side 
has been removed to the other. Thus the Flatfishes in 
their normal state are of a structure that in all other 
animals would be an extremely remarkable monstrosity, 
and if they were unusual, we should undoubtedly re- 
gard them as the most wonderfully formed of all crea- 
tures; but now that we see this animal form so often, 
it generally excites but slight attention. A Flatfish 
whose eyes were situated like those of other animals, 
would be a monster . . . In spite of this deformity of 
the head, however, the cranial bones are almost exactly 
the same as those of other fishes, being abnormal only 
in shape and position. In the other parts of the body, 
“ Ear. Mer., tome 3, p. 446. 
h Tr. cl. Pitches, part. 11, sect. 3, p. 480, tab. XXII, fig. 2. 
c See Collett. 1. c. 
d Family Heterosom.es , Dum., Zool. Anal. (1806) pp. 119 and 
Ainer. Phil. Soc. Philad., n. ser., vol. XIV (1871), p. 456. 
e Bull. Acad. Roy. Belg. Brass., tome XX, part. Ill, p. 206. 
f Ofvers. Vet.-Akad. Fork. 1854, p. 173; Vet.-Akad. Handl., 
g Overs. D. Vid. Selsk. Fork. 1863, p. 145; 1876, p. 174, t 
h Trans. Linn. Soc., vol. XXV (1866) p. 263, tab. 29 — 32; 
'bital region and the mouth are unsymmetrical in the adult 
the same side of the body. 
too, there is a certain lack of symmetry, though to a 
much more restricted extent. The mouth is always 
somewhat awry, and the teeth different on each side, 
being often wanting on the upper or eye side; the 
pectoral fin on the under or blind side is smaller; the 
vent is turned towards the same side etc. But the 
most striking difference between the sides is that the 
eye side is coloured, generally with a dark, brownish 
tint, and the blind side white. This peculiarity, as 
well as the position of the eyes, is very nearly connected 
with the singular manner in which these fishes move. 
They swim lying fiat on one side, with the blind" side 
turned towards the bottom, the eves and the more de- 
veloped colour being turned upwards to the light . . . 
Sometimes, however, we meet with specimens in which 
the blind side is spotted or partly of the same colour 
as the eye side.” 
This want of symmetry in the Flatfishes has been 
a subject of investigation for many naturalists of recent 
times. Van Beneden®, Malm 7 , Steenstrup 5 ’, Traquair*, 
133; Ichth. Anal. (1856) p. 354. Order Heterosomata in Cope, Trans. 
Bd. 7, No. 4, pi. 1 and 2. 
ab. I— IV. 
Proc. Roy. Phys. Soc. Edinb. 1864—1865, p. 215. 
Scandinavian Fishes. 
46 
