ACCESSORY EYES 261 



such as most of the Glyphocrangons (Fig. 52), in 

 which the eyes are of good colour and of singular 

 bigness : here, as daylight is entirely excluded, we 

 may, perhaps, trace the influence of phosphorescence. 



In a good many of the large-eyed deep-sea shrimps 

 (Caridea), and in a few of the prawns {Peneidea) small 

 accessory eyes are present, either on the eye-stalk itself 

 or at the end of a small branch of the eye-stalk. The 

 figure of Parapandalus spinipes (Fig. 53) shows a pair 

 of these accessory eyes, which, it should be mentioned, 

 some authorities are inclined to regard as phosphor- 

 escent organs. 



If it be true that the active inhabitants of the dim 

 twilight of the upper part of the abyssal slope are usually 

 characterised by eyes of owl-like magnitude, yet when 

 we are dealing with sedentary or burrowing species, or 

 even with many active species that we feel sure must 

 live far down in the abyss, it is usual to find that the 

 eyes are small or in some way imperfect. For instance, 

 in the oceanic shrimps of the family Pandalidce, which 

 are often taken in less than 200 fathoms water, the eyes 

 as a rule are large, and accessory eyes are common ; but 

 Dorodotes reflexus, a member of this family, which, from 

 its colour and from the density of its exoskeleton as well 

 as from the fact that during all these years it has never 

 yet been captured unless the dredge has gone below 

 1000 fathoms, we have good reason to regard as a 

 true denizen of the deep sea, has particularly small 



