148 DARK UNFATHOMED CAVES OF OCEAN 



represented in the deep seas of India by three distinct 

 species, besides the species I^Homola orientalis) dis- 

 covered off the Philippines by the Challenger, This 

 Ho7nola megalops is, like Nephrops thomsoni, remark- 

 able for the large size and intensely black colour of 

 the eyes, from which we may infer that at a depth of 

 about 200 fathoms there is still some light for animals 

 whose eyes are big enough and powerful enough to 

 catch it. With these two visually well-endowed crus- 

 taceans we dredged a number of specimens of the 

 blind lobster {Nepkropsis stewarti), whose eyes are 

 colourless rudiments, although the eyestalks are 

 present. Both Nephrops and Nephropsis are as closely 

 as possible related to the ordinary edible lobster 

 {Homarus vtUgaris), all three forms being probably 

 descended from a common ancestor which possessed 

 eyes of ordinary size attached to movable eyestalks. 

 Of the descendants of this ancestral form some would 

 have retained eyes of average size and strength, and 

 these would have remained in comparatively shallow 

 and well-illuminated water, and would have given rise 

 to the common lobster of the fish-market {Homarus), 

 But others, urged by that unrelenting competition 

 which is felt throughout the whole of organic Nature, 

 would have emigrated to the depths, that to ordinary 

 lobsters are Cimmerian darkness ; and of these emi- 

 grants some — since inequality of endowment is one 

 of the inevitable facts of existence — would have had 



