EYES IN DEEP-SEA ANIMALS 35 



the eyes are either dwindling or have quite disap- 

 peared. An instance in point is supplied by the 

 Crustacea, many of whom have not only lost their 

 eyes, but have also lost the stalk which bore them ; 

 but amongst the Crustacea some genera, such as 

 Bathynomus, have enormous eyes with as many as four 

 thousand facets. It is noticeable that this creature 

 has its eyes directed downwards toward the ground 

 and not upwards, as is the case with its nearest allies. 

 On the whole the Crustacea lose their eyes more 

 readily, and at a less depth, than fishes. Many of the 

 latter — e.g., Ipnops — are blind, and in others the eyes 

 seem to be disappearing. Thus, amongst the deep- 

 sea cod, Macrurus, those which frequent the waters 

 down to about 1,000 fathoms, have unusually large 

 eyes, whilst those which go down to the deeper 

 abysses have very small ones. Many of the animals 

 which have retained their eyes carry them at the end 

 of processes. Chun, in his brilliant ^account of the 

 voyage of the Valdivia, has figured a series of fishes 

 whose eyes stand out from the head like a pair of 

 binoculars ; and similar ' telescope ' eyes, as he calls 

 them, occur on some of the eight-armed cuttle-fish. 

 The larva of one of the fishes has eyes at the end 

 of two stalks, each of which measures quite one-fourth 

 of the total length of the body. 



The colour of the deep-sea creatures also indicates 

 the darkness of their habitat. Like cave-dwelling 

 animals, or the lilac forced in Parisian cellars, many of 

 them are blanched and pale ; but this is by no means 

 always the case. There is, in fact, no characteristic 

 hue for the deep-sea fauna. Many of the fishes are 

 black, and many show the most lovely metallic sheen. 

 Burnished silver and black give a somewhat funereal, 

 but very tasteful appearance to numbers of deep-sea 

 fish. Others are ornamented with patches of shining 

 copper, which, with their blue eyes, form an agreeable 



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