shufeldt] THE PHYSIOGNOMY OF FISHES 143 



very large in order to gain the light to see, as in examples already 

 described; but where the light is permanently withdrawn the 

 species in time loses its eyes entirely, instances of which are to 

 be observed in the famous blind fishes of the Mammoth Cave of 

 Kentucky and elsewhere in the United States. Amblyopsts 

 spelaus, a colorless species, is the name of the latter form, and, 

 being very tenacious of life, they make most interesting species to 

 study in aquaria. 



When we come to look into the matter of eyes, however, and the 

 part they play in the physiognomy of many fish, there is no 

 stranger form in all the world presenting itself for our considera- 

 tion than the American "Four-eyed fish" (Anableps dovii. Fig. 9). 

 This species occurs at Panama in the Canal Zone. In it the 

 integuments of the eye are divided into upper and lower portions 

 by a dark-colored, transverse band of the conjuntiva, while at 

 the same time the pupil is incompletely divided into two by a pair 

 of lobes projecting from each side of the iris. This gives the fish 

 two pupils in either eye, in either orbit. One of these gazes 

 upwards and the other lateral-wise, the first employed for water 

 use, and the other for objects in the air; it is a surface species 

 that subsists upon insect food. 



Related to the Puffers we have the Porcupine fish (Diodonhystrix, 

 Fig. 16), and a most remarkable profile it possesses. It has a 

 bony coat -of -mail, from which projects scores of needle-pointed 

 spines of many sizes, while in its mouth it has but two teeth 

 surrounded by fleshy lips. These fish grow to be three feet in 

 length, and their bellies are moderately inflatable as in their 

 allies, the Puffers and Swell-fish. My collection contains a fine 

 skeleton of one taken in Bermuda by the collectors of the New 

 York Aquarium. 



Vertically slit mouths are by no means confined to the deep- 

 sea species, for our surface Stargazers (Katltetostoma albigutta) 

 present the same arrangement, and their profiles are rendered 

 correspondingly remarkable (Fig. 18). These species have a way 

 of settling down in the mud or sand of the bottom until the mouth 

 is flush with the latter. Here thev He in wait for the small fishes 

 which form their food. 



