88 BULLETIN OF THE 
dinary development, in only a part of the genus, of a special sensory 
apparatus peculiarly useful to a fish unable, for any cause, to see, 
points the same way, [i e. to the supposition that this genus has a 
shorter subterranean history than Amblyopsis,] and gives evidence of a 
progressing adaptation of these fishes to their unusual abode. The in- 
termediate relation of the sensory tubercles of Chologaster to the much 
smaller ones of young fishes and the permanent papille of Amblyopsis, 
points out the evident origin of the last through the permanency 
and higher evolution of structures evanescent in the young.” This is 
probably the clearest case furnished by vertebrates of the loss of sight 
being recompensed by a higher development of the tactile sense. 
As regards the tactile papilla in the Cuban blind fish (Lucifuga), Put- 
nam (272, p. 9), who examined a specimen sent to the Museum of Com- 
parative Zoólogy by the discoverer of the fish, Professor Poey, says: “In 
the Cuban blind fish we find ciliary appendages on the head and body ` 
quite distinctly developed, evidently of the same character as those of 
Amblyopsis, and answering the purpose of tactile organs. . . . There are 
eight of these on the top of the head, . . . and quite a number arranged 
in three rows on each side of the body, showing that the tactile sense 
is well developed in these fish." 
This, so far as I am aware, is all that is known on the subject, and 
can be regarded as furnishing nothing more than a probability that 
touch papillas have been here developed to compensate the fish for sight- 
less eyes. The writer just quoted remarks further, that it is singular 
that the barbels on the jaws, so commonly found in the Cod family and 
its allies (to the latter of which the Cuban fish belongs), are entirely 
wanting. As is well known, Lucifuga is a cave dweller, and consequently 
the conditions which have produced its rudimentary eyes are more 
similar to those that have produced the corresponding change in Am- 
blyopsis than to those that have had the same effect on Typhlogobius. 
And this fact may strengthen the probability above referred to; for, 
from the difference in conditions of life, Amblyopsis and Lucifuga are in 
rj 
all probability much more active than Typhlogobius, and this would 
make the tactile sense more useful to the first two species than to the 
last one. 
We will now notice the condition of the blind deep-sea fishes with 
reference to the touch papille. The three forms described by Gün- 
ther (80), Typhlonus nasus, Aphyonus gelatinosus (p. 548), and 
Ipnops murrayi (p. 585), are all without barbels, and, so far as 
known, other special tactile structures. The two genera first named 
) 
