66 
One more remarkable instance of protective resemblance I ob- 
served here in Panama (— and, if I remember right, also in Japan 
a. 0. places; but it was only here in Panama that I became aware 
of the probable explanation —). Some young fishes (apparently of the 
genus Atherina) were frequently observed swimming in small shoals 
in the surface in a peculiar irregular way, reminding one a little of a 
flock of Gyrinidæ — not at all that I mean to say they have a protect- 
ive resemblance to the Gyrinidæ, which would, of course, mean 
nothing in the sea. They are silvery white and look like small shining 
spots; in my mind there is no doubt that they are mimicking 
the drops of water, so often seen floating for a while 
on the surface of the sea. It is, of course, impossible to give 
an impression of this resemblance through a figure from preserved 
specimens, the more so as they lose their shining appearance on 
preservation. But on seeing them moving along in the way de- 
scribed one can hardly doubt that this is the meaning of it. 
In this connection I must mention a peculiar habit of some 
young fishes, first noticed by Malm?) and G. O. Sars?), viz. that 
they are generally found under large Medusæ. Malm found the young 
Caranx trachurus in Cyanea capillata, feeding on the ovaries of 
the jellyfish. Sars found the young Gadus callarias and æglefinus 
under the Cyanea and came to the result that they come here 
in order to eat the small animals which the jellyfish captures 
with its tentacles — and in return do the jellyfish the service of 
eating the Hyperias, which devour the jellyfish. Sars also found 
the young Gadus under Aurelia aurita and even under pieces of 
algæ and other things floating in the surface. He has also thought 
ihat it might possibly be in order to seek protection from their 
enemies that the young fishes seek a shelter under the jellyfish, but 
did not find that explanation satisfactory. More recently L. Scheu- 
ene has made some experiments with young Gadus merlangus 
') Malm. Ichthyologiska anmårkningar. Ofvers. Vetensk. Akad. Fårhandl. 
1852. p. 228 
KR) G. O. Sars. Indberetning til Departementet for det Indre om de af ham 
i Aarene 1864—78 anstillede Undersøgelser angaaende Saltvandsfiske- 
rierne. Christiania. 1879. p. 37. 
” L.Sche euring: Beobachtungen iber == Parasitismus pelagischer Jung- 
fische. Biol. Centralblatt. XXXV. 1915. p- 
