Luminous Animals. 259 



of 190 species to the list of luminous marine animals. I have 

 already stated the reasons why I cannot as yet give even the 

 names of many of these, of which a considerable number are 

 certainly new, or nondescript animals. That subject must be 

 reserved for a different species of communication ; but I shall 

 here add at least the generic names of those possessed of lu- 

 minous properties, of which the genera are known ; since, even 

 in these, some of the species are still unsettled and many are 

 new. 



Among these, the most conspicuous are about twenty small 

 species of Medusa, in addition to those already known to be lu- 

 minous. In the ancient genus Cancer, a considerable number 

 of Squillse were also found possessed of this property. In the 

 genera Scolopendra and Nereis five or six were luminous, 

 being all the species that came under my observation. Of the 

 i-emaining known genera in which luminous species were ob- 

 served, I shall forbear to give any numerical account, but 

 simply add that they consisted of Phalangium, Monoculus, 

 Oniscus, lulus, Vorticella, Cercaria, VibriQ, Volvox. To these I 

 may also add, among the fishes, a new species of Leptocephalus. 

 The rest consisted of new genera, or, at least, of animals which, 

 for want of correct descriptions and of figures, cannot be re- 

 ferred to any as yet to be found in authors, and of which I 

 trust at some future period to give those drawings and descrip- 

 tions which are in my possession. It is sufficient for the present 

 purpose to have shewn that the list of luminous animals is very 

 extensive, and to have given this notice of the means used in 

 investigating this object, together with such hints as may be 

 useful to others ; little doubting that their labours v/ill ultimately 

 prove this beautiful and remarkable property to be possessed by 

 every one of the inhabitants of the ocean. 



But I must not conclude this paper without noticing a cir- 

 cumstance which confirms the opinion stated in the former 

 essay respecting the residence of many fish in depths which 

 accQrding -to Mr. Bouguer's observations, must be supposed 

 inaccessible to the light of the sun ; and in which, without that 

 afforded by their prey, it is difficult to understand how they 



