PHOTOGENIC M AMINE ANIMALS. 11 



Grube subsequently found that Polycirrus likewise excels in the 

 brightness of its phosphorescence, and the ease with which it is 

 elicited. Mere blowing on the water of the dissecting-trough 

 suffices to produce it in the British species — the most vivid pale 

 bluish luminosity gleaming for a moment along every one of the 

 mobile tentacles, often elegantly disposed in a stellate manner. 

 Thelepus, another example of the group, is only faintly phos- 

 phorescent during life, but when decomposition has advanced it 

 shines in the water with a pale lambent light, somewhat like 

 phosphorus in air. The transparent pelagic Tomopteridce present 

 on the feet certain peculiar structures which were formerly sup- 

 posed to be eyes or simply glandular organs. Greef found these 

 to be luminous. 



So far as can be observed in this group, viz. the Annelids, 

 there is little in the habits or surroundings of the phosphorescent 

 species to explain the occurrence of the phenomenon. The most 

 diverse conditions prevail. Thus Tomopteris is pelagic through- 

 out its entire existence. Polynoe floccosa lives in the free con- 

 dition under stones between tide-marks, while those of the same 

 genus are commensalistic with the Terebellidce in tubes. The 

 phosphorescent species of Terebellids are tubicolar, or occur in 

 fissures of rocks. Chatopterus dwells in tough tubes of a parch- 

 ment-like secretion covered with pebbles, stones, shells, and sea- 

 weeds. To suppose that the Polynoids attract prey for the 

 benefit of the Terebellae or themselves is to endow them with 

 properties analogous to those the older naturalists ascribed to 

 the Pea-crabs in the Horse-mussel. It is unlikely that they are 

 furnished with light to attract marauding fishes or Crabs, for 

 they are in tubes immersed in sand, beneath stones, or in obscure 

 chinks and fissures of muddy rocks, boulders, and old shells. It 

 can hardly be affirmed that they are protected because they are 

 luminous, since many species which are not so have exactly the 

 same habits and shelter ; while other phosphorescent forms are 

 either pelagic or devoid of such a safeguard. No reliable de- 

 duction can be made as to the function of this endowment. 



Amongst the lower marine Arthropods one of the most inter- 

 esting examples occurs in a gigantic Pycnogonid (Colossendeis 

 gigas), recently dredged by Dr. Alcock at 922 fathoms near the 

 Andaman Islands. It is blind, and appears to feed on oceanic 



