258 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
two rays are about twice as long as the others and for about half their length they 
project freely below the rest of the tin. In the hake all of the rays of this tin are 
suppressed save these modified free rays, so that the tin is filliform, branched at the 
end. Microscopic examination shows that the terminal buds are more abundant on 
the more highly modified tins. The hake also has a free filament on the dorsal fin 
produced by the extension of the third and fourth rays beyond the others. I have 
not examined this free filament microscopically, but know that it receives communis 
fibers from the r. lateralis accessorius, and have no doubt that it also has numerous 
terminal buds, as the experiments show it to be very sensitive to gustatory stimuli. 
The pollock have very large eyes and are excellent visualizers. When food is thrown 
into the water, they dart for it and in general the}' take their food by the visual reflex. 
So keen is the vision that it would be difficult to carry on any experiments, such as I 
have done with the other two species, without first blinding the fish. Nor do they 
habitually drag the bottom with the free ventral fin rays as the others do. I have, 
therefore, not devoted much attention to this species, preferring to study more care- 
fully those species in which the gustatory reflex plays the greater part in the life of 
the fish. 
The hake ( Vrophycis tenuis). — These fishes, like the tomcods, readily adapt 
themselves to life in captivity, and are easily experimented upon in small tanks. 
They are excellent visualizers, though not so much so as the pollock. When bits of 
meat are thrown into the water they usually catch them before they fall to the 
bottom, and their keen vision makes difficult such experiments as I carried on with 
the cat-fishes. They do not seem to recognize by sight food lying on the bottom, but 
only when it is in motion. But bits of meat, fish, or clam lying on the bottom are 
usually found by the aid of the free ventral tins. These fishes spend much of their 
time in slowly swimming in an apparently aimless manner close to the bottom of 
their tank. During these movements the filamentous pelvic fins are so held that 
their tips drag the bottom. These fin rays are quite long, and they are usually 
directed obliquely forward, outward, and downward, with the two branches of each 
fin widely divaricated, so that the four tips touch the ground in a line transverse to 
the body axis at about the level of the mental barblet. In this way the bottom under 
the fish and for a short distance on either side is thoroughly explored as the fish 
swims over it. and all food particles with which the barblet or free fin rays come in 
contact are taken by a quick and precise movement similar to that set off in the 
siluroids by contact with their barblets. Bits of meat or clam on the end of a slender 
wire could be laid on the bottom of the tank and then slowly moved up under or 
behind the fish and the reflex from the ventral fins tested in this way. Such experi- 
ments, however, had to be made with great caution and many times repeated to rule 
out possible visual sensations which likewise call forth an immediate reflex. 
Bateson ('90, a) records similar reactions with the rockling ( Motella ), a gadoid 
fish with the same general structure and distribution of terminal buds as the hake, 
but with better developed barblets. (On the structure of the pelvic fins of Motella 
compare Bateson’s account on p. 211 with that on p. 234 of the same volume.) 
Bateson, moreover, got the same reflex with fishes which had been blinded, and I have 
not thought it necessary to repeat this experiment, for my fishes give sufficiently 
clear evidence that this reflex from the fins is wholly independent of vision. We 
