THE EYE-LIKE SPOTS IN FISHES. 
223 
were spared too hasty a generalization, for from the same depths 
the dredge of the same ship brought up specimens of the genus 
Munida , in which the eyes were developed to a very great size. 
What is true of Crustaceans is true also of fishes, as the 
following quotation from Dr. Gunther will show better than 
any words of ours : 4 The organ of sight is the first to be 
affected by a sojourn in deep water. Even in fishes which 
habitually live at a depth of only eighty fathoms, we find the 
eye of a proportionately larger size than in their representatives 
at the surface. In such fishes the eyes increase in size with 
the depth inhabited by them, down to the depth of 200 fathoms, 
the large eyes being necessary to collect as many rays of light 
as possible. Deyond that depth small-eyed fishes as well as 
large-eyed occur, the former having their want of vision com- 
pensated for by tentacular organs of touch, whilst the latter 
have no such accessory organs, and evidently see only by the 
aid of phosphorescence. In the greatest depths blind fishes occur 
with rudimentary eyes and without special organs of touch.’* 
Interesting as these cases are, and that the more because 
there still remains to be solved the interesting problem raised 
by two lines of development being followed by animals living 
under apparently exactly the same conditions, and starting from 
exactly the same point, the ordinary vertebrate or crustacean 
eye, we must turn from them to give an account of a struc- 
tural arrangement found in various fishes, which will be seen to 
he not distantly connected with the question of the phosphores- 
cent light of the deep-sea. Of one of these fishes the lamented 
Willemoes-Suhm wrote home, 4 Wie ein leuchtender Stern hing 
einer im Hetz, als er Nachts herauf kam.’ 
Among the bony fishes ( Teleostei ), and in that division which 
is distinguished by having the air-bladder communicating by 
an air-duct with the anterior portion of the intestine ( Physostomi ), 
and especially among the members of the group which always, 
or generally, live at great depths, there are sometimes found — 
as for example in Scope his or Astronesthes — one or two rows of 
small rounded bodies, which are chiefly distributed along the 
sides of the body, although sometimes, as in the latter of the 
two just-named genera, they are also very well developed in 
front of the proper eye. In Ipnops , a form first collected by 
the officers of the Challenger exploring voyage, and which is 
placed by Dr. Gunther next to Scopehis, there are indeed none 
of these bodies ; but the eye of this fish appears to have lost its 
function and to have taken on that of a phosphorescent organ. 
* To this may be added the case of the Decapod Crustacean, Willemoesia 
(so named after the late naturalist Willemoes-Suhm, of the Challenger 
Expedition) ; one species of this form was dredged in 1900 fathoms, and the 
genus is distinguished by having neither eyes nor eye-stalks. 
