FLYING FISHES AND THEIR HABITS. 513 



yet set at rest. Of course no flyiiiji; Hsh can raise themselves in the 

 air by means of their wiiigs alone." 



Schmidtlein believed that their power of flying was [)robably not 

 far behind that of the Exocoetids, so far as the fishes have been 

 observed in nature, but in the aquarium experimentation on this 

 question is not to be thought of. On the contrary, the authorities 

 of the Naples station liave to protect the basin for these fishes witli 

 bars and nets to prevent their escaping, because they would other- 

 wise fly either through the window into the open air or to either side 

 into the adjoining tanks. And, as a matter of fact, the station loses 

 a rather large number of the fishes because they jump out and fall 

 against the walls, or on the bridge over the aquarium, and perish 

 there. 



II. 



The Dactylopterids are naturally carnivorous, but their food is 

 determined by the size of the mouth and their environments. Ac- 

 cording to Schmidtlein, their small mouth permits them to swallow 

 only small morsels; therefore they like to take crustaceans, such as 

 shrimps {('raitr/on or (Uuujo) and prawns (PaJaemon), young crabs, 

 and tiny fishes, which they find dead on the bottom. 



III. 



W. P. Calderwood and G. P. Bidder told Ernest Holt (1S!)8) '* that 

 when a Dactylopterus w^as placed in a tank at Naples containing 

 some small sharks the latter bit jneces out of its pectorals, a liberty 

 resented l)y violent grunting." It is added that " gurnards and 

 dories also grunt inider circumstances of discomfort, the sounds 

 being of the nature which appears from experiment to l)e pci-ceptible 

 by fishes. They ma}' possibly subserve^ a function which is in part 

 protective." 



The Dactylopterids emit sounds under certain conditions, both in 

 the water and out of it. While Calderwood was killing a couple of 

 specimens "" sounds exactly similar to those of the (lurnard were 

 distinctly heard, and simultaneously with each sound a distinct con- 

 traction of the bladder could be felt from the exterior. These con- 

 tractions were quite independent of any movements of the mouth or 

 operculum." Schmidtlein never heard the sounds emitted voluntarily 

 under water, nor t)bserved the movement of the gill covers which 

 produce them. P]xperiments relating to this subject wei-e made by 

 him and details promised for another place, but never published. 

 The testimony of CalderAVOod and I^idder, however, supplies the defi- 

 ciency in Schmidtlein's observations. 



The sounds thus noticed are produced by the action of four muscles 

 SM 1904- 33 



