XOTE ON THE EYES OF DEEP SEA FISHES. 

 By R. von Lendenfeld, Ph.D. 



In a short note which I published some time ago (1), concerning 

 the life history of the New Zealand Frost fish, Lepidopus caudatus, 

 I mentioned the fact, that Lepidopus caudatus had very large eyes, 

 and deduced from this, that it was a Deep Sea Fish. 



Referring to this note, Mr. Arthur (2) points out that large eyes 

 cannot be a criterion of deep sea fish, because many deep sea fishes 

 have small eyes, or no eyes at all. There is no doubt that numerous 

 deep sea animals have lost their eyes in the same manner as the 

 blind mole, but at the same time I would like to point out that 

 very large eyes are certainly a proof that the animal which possesses 

 them lives in a dark place in the case of this animal, being marine, 

 in deep water. 



The progeny of an ordinaiy surface fish, which may have quitted 

 the shallow water and taken up its abode in the dark abyss could 

 not have migrated to a greater depth very quickly, but must 

 necessarily have been many generations doing it. 



If the eyes of the fish oi'iginally were good and the migration 

 was effected very slowly, there is no doubt, that the species may 

 have adapted itself in the ordinary manner to the slowly changing 

 amount of light, by its eyes becoming continually enlarged. On 

 the other hand if the eyes of a species originally were not very good 

 and the migration was a rapid one, there w T as not sufficient time for 

 adaptation, and the eyes were of less use the deeper the species 

 migrated, so that they finally became rudimentary, because they 

 were useless. 



(1) B. v. Lendenjeld. Ueber Lepidopus caudatus. Zoologischer Auzeiger. 

 Band VII. Seite 1SS3. Translated into English. New Zealand Science 

 Journal. Vol. II., p. 108. 



(2) Arthur. Notes on the occurrence of the Frost Fish. New Zealand, 

 Journal of Science. Vol. II., p. 157. 



