14 HOVLE, P terygiotetUJiis viargaritijcra. 



they closely resemble the branchial organs in their minute 

 anatomy. 



In conclusion, the question may be asked, what evidence 

 is there that these bodies are really luminous organs ? The 

 first argument in favour of an affirmative answer is a figure 

 given by Chun of a cephalopod in which the luminosity 

 was actually observed by him on board the " Valdivia,"* 

 and in which the organs so closely resemble in arrange- 

 ment those above described that one would naturally 

 imagine the two forms to be of the same genus if not the 

 same species. From information given me by Professor 

 Chun, I conclude they must be rather distant systematically. 

 Another argument in favour of the luminous function of 

 these organs is to be found in their structure, which recalls 

 the arrangement described by Joubin, and found by myself 

 in some other forms. Notably is this the case with the 

 bodies I have called "scales" which closely resemble the 

 " mirror-cells " of Histioteutliis.\ 



With respect to the functions of the different parts 

 of the apparatus, I feel no doubt that the central mass 

 is the source of light ; its nerve supply obviously suggests 

 this view. The posterior cup I should regard as a reflector 

 and the internal cone and anterior cap as playing the part 

 of lenses. 



Finally, I desire to express my indebtedness to 

 Mr. J. T. Wadsworth, of the Owens College Zoologica. 

 Laboratory, for the sections on which these observations 

 have been made. 



* " Aus den Tiefen des Weltmeeres," Jena, 1902. 



t Joubin, " Recherches sur I'appareil lumineux d'un cephalopoda, His- 

 iioteitthis ruppeliii Verany," Rennes, 1S93, p. 14. 



