22 H. N. MOSELEY. 



pvotluctj and of no use to the animal, although, of coarse, 

 in some instances it has been turned to account for sexual 

 purposes, and may have other uses occasionally. There is 

 no reason why a constant emission of liglit should be more 

 beneficial than a constant emission of heat, such as takes 

 place in our own bodies, and it is quite conceivable that 

 animals might exist to which obscure heat-rays might be 

 visible, and to which, therefore, men and mammals generally 

 would appear constantly luminous. 



However, be the light beneficial to them or not, it seems 

 certain that the deep sea must be lighted here and there by 

 greater or smaller patches of luminous Alcyonarians, with 

 wide intervals, probably, of total darkness intervening. Very 

 possibly the animals with eyes congregate around these 

 sources of light. 



The phosphorescent light emitted by three species of deep- 

 sea Alcyonarians was examined with the spectroscope and 

 found to consist of red, yellow, and green rays only. Hence, 

 were the light in the deep sea derived from this source, in the 

 absence of blue and violet light, only red, yellow, and green 

 colours could be effective. No bhie animals were obtained in 

 deep water, but blue animals are not common elsewhere. It is 

 remarkable that almost all the deep-sea shrimps and schizo- 

 pods, which were obtained in very great abundance, are of an 

 intense bright scarlet colour, differing markedly in their in- 

 tensity of colour from shallow-water forms,, and having 

 apparently for some purpose developed an unusually large 

 quantity of the same red pigment matter which colours small 

 surface Crustacea. 



A brilliant green colouring matter was found in some deep- 

 sea Annelids. 



No doubt in many cases the colouring of the deep-sea 

 animals, as in the case of the purple Holothurians, is useless 

 and only a case of persistence. The madder colouring of 

 some of the soft parts of the Corals may be in like case, but 

 possibly useful for attraction of prey, being visible by the phos- 

 phorescent light. Nearly all, if not all, of the fish certainly 

 living on the bottom in the deep sea were of a dull black or 

 quite white and semi-transparent. 



I regret much that I did not examine deep-sea fish with 

 regard to the existence and amount of hfemoglobin to be found 

 in them. 



The same colouring matters exist in deep-sea animals which 

 are found in shallow-water forms. Polyperythrin is found 

 abundantly in surface-swimming Ilhizostomffi and in deep-sea 

 Corals and Actiniae Antedonin occurs in a shallow water 



