THE EYE OF SALMINCOLA EDWARDSII OLSSON. 409 



GROSS STRUCTURE OF THE EYE. 



The eye of Salmincola edwardsii is located in the cephalo- 

 thorax, occupying a central position, directly below the loop 

 of the attachment filament. Text figure A, which is a dorsal 

 view of the larval free-swimming stage, shows the location of 

 the eye (e). When viewed from the dorsal or the ventral surface 

 of the free-swimming larva, the eye appears as a more or less 

 x-shaped, reddish-brown pigment blotch in which three ocelli 



TEXT FIGURE A. Dorsal view of free-swimming larva of Salmincola edwardsii 

 (Lernceopoda edwardsii), showing the position of the eye. X 86.8 a./. = attach- 

 ment filament, ant.i = first antennae, e. = tripartite eye. y. = yolk. 



can be distinguished. Two of these are situated dorso-laterally, 

 while the third is placed immediately beneath them, occupying 

 a median position. This is shown in Figs. I and 2, which are 

 enlarged drawings of the eye, as seen respectively from the 

 ventral and dorsal sides of the animal. 



When favorable preparations of the eye, from which the pig- 

 ment has been extracted, are studied under the high power 

 objectives, the external structure of the ocelli becomes more 

 apparent. In such preparations, each ocellus is seen to be 

 embedded in a semi-lunar cup (Figs. I and 2, c), and is covered 

 by a cuticular outer surface, which is divided up into narrow 

 bands by means of transverse striations. These bands are 



