SCOEPIONS — LIGHT-ORGANS OF EUPHAUSIA. 161 



structure of its eyes. These can hardly be regarded 

 as homologous with the compound eyes of insects and 

 Crustacea, but appear to have originated independently. 

 They have, indeed, hardly anything in common, except 

 that of being compound eyes. 



Lastly, I may allude to the eyes of scorpions, 

 which, though very different from those of Limulus 

 in appearance, in Lankester's opinion approach them 

 more nearly in essential constitution than any other 

 known eyes. 



Before quitting this part of my subject, I must 

 mention the curious eye-like oigans of Euphausia. 



Euphausia (Eig. 110) — a shrimp-like crustacean, be- 



Fig. 110. —Euphausia pellucida (after Sars). l.o.. Luminous organ. 



longing to the same group as Mysis — and some of its 

 allies, are remarkable for possessing at the base of 

 some of the thoracic legs, and on the four anterior 

 abdominal segments, luminous eye-like organs. They 

 form small bulbs, each containing a vitreous body, some 

 pigment, a lens, and a fan-shaped bundle of delicate 

 fibres, and are very conspicuous from their beautiful 

 red color and glistening lustre. 



