1910.] ox THE PIIOTOPIIOllES OF DECAPOD CRUSTACEA. 639 



Centenary of Philip Henry Gosse, F.N.S. 

 BornAprUQ, 1810; died Aug. 23, 1888. 



The Secretary exlubiteil the set of the works of PhiUp Henry 

 Gosse ill the Society's Library and gave a brief summary of his 

 contiibiitioiis to science, upon which he placed a very liigh value. 

 The Chairman and Prof. A.. Sedgwick, F.R.S., added their testi- 

 mony to his place in Zoological history ; Dr. Henry Woodward, 

 F.R.S., gave some personal reminiscences; and Mr. Edmund Gosse, 

 Librarian of the House of Lords, the son and biographer of Gosse, 

 thanked the Society for their notice of his father's centenary. 



The following papers were read : — 



1. Notes on the Photophores of Decapod Crustacea. 

 By Stanley Kemp, B.A.* 



[Received March 1, 1910. J 



(Plates LII.-LIY.t) 



Two different methods of producing light are known among 

 Crustacea. In the vast majority of species possessing this power 

 the organ is of a glandular nature, excreting drops of oily fluid 

 which become luminous on reaching the water. The process is 

 probably one of oxidation, though from the results of Giesbrecht's 

 experiments + it would seem that very small quantities of free 

 oxygen will suffice. 



Certain Decapods, such as Folycheles 2)hospho7'iis, appear to pro- 

 duce light in this way, while in others, such as Aristeus coruscans 

 and Heterocarpus alphonsi, the excretions fi'om the antennal 

 glands have been noticed to be brilliantly phosphorescent §. 

 Both these phenomena seem to be exceedingly rare among 

 Decapods. 



The second method of producing light, and it is only with this 

 type that the present paper is concerned, is by means of photo- 

 phores, compound luminous organs which do not excrete a fluid ; 

 they are in most cases provided with a lens and sometimes also 

 with a reflector. Very little is known of the chemical processes 

 which are involved in this type of phosphorescence. The essential 

 feature, as in the case of the glandular organs, is doubtless one 

 of oxidation, and it is probable, as Alcock has suggested, that the 

 oxygen is conveyed to the photophoie by means of tlie blood. 



Among Crustacea,, photophores are known only in the Euphau- 

 siacea and in the Decapoda. In the former group they are very 

 highly specialised and occur in practically all the species known, 



* Communicated by Dr. W. T. Caiman, F.Z.S. 

 t For explanation of the Plates see p. 650. 

 X Giesbreclit, Mitth. Zool.-Slat. Neapel, ii. 1895, p. 648. 

 ^ See Alcock, ' A Naturalist in Indian Seas,' 19U2. pp. 134 & 135. 



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