The Grayling and the Smelt 255 
tactile organs (as in Bathypterois and Benthosaurus), and experi- 
ments show that barbels may become organs of touch adapted 
to aquatic life, sensitive to the faintest movements or the 
slightest displacement, with power to give the blinded fishes 
full cognizance of the medium in which they live.” 
Rondeletiide.—The Rondeletiide are naked black fishes with 
small eyes, without adipose fin and without luminous spots, 
ee eee 
Fic. 260 —Cetomimus gillii Goode & Bean. Gulf Stream. 
taken at great depths in the Atlantic. The relationship of these 
fishes is wholly uncertain. 
The Cetomimide are near allies of the Rondeletiide, having 
the mouth excessively large, with the peculiar form seen in the 
tight whales, which these little fishes curiously resemble. 
Myctophid#.— The large family of Myctophide, or lantern- 
fishes, is made up of small fishes allied to the Aulopide, but 
Fic. 261.—Headlight Fish, Diaphus lucidus Goode and Bean. Gulf Stream. 
with the body covered with luminous dots, highly specialized 
and symmetrically arranged. Most of them belong to the 
deep sea, but others come to the surface in the night or during 
storms when the sunlight is absent. Through this habit they 
are often thrown by the waves on the decks of small vessels. 
7 
