646 MR. STAXLEY KEMP OS THE ['•^P'"' 19, 



ori(iins wiiicli, when sectioned, show no definite structnre. In a 

 freshly canj,dit specimen each appears as a deep l)Uie spot circum- 

 scribed by a belt of colourless tissue. 8uch a distribution of 

 pigment .seems to afford considerable support to the view, 

 advanced by Couticre, that all the )>hie .spots represent luminou.s 

 organs. 



An examination of yoinig specimens of A. dehilia shows thnt, 

 us might have been expected, the complex organs are those which 

 appear fir.st. The eggs are very large and consequently the young 

 are lil)erated in a rather advanced stage. The eai-liest-known 

 larva pos.se.sses twelve luminous organs, viz., tho.se on the pleopods 

 and behind the fifth pair of legs. A little later the other com- 

 pound photophores behind the protopodites of the uropods appear 

 and simultaneously with them certain of the simple 0]-gans, At 

 every succeeding moult fresh .spots of blue pigment appear, until 

 in the large.st individual known they have reached the total of 

 one hundred and forty-seven *. 



The Photoi'iiores of lIoPLorriours. 



Coutiere {loc. cit. 1905, p. 1) first desci-ibed these organs in a 

 species which he named Iloplophoras grimaldii. Thanks to the 

 kindness of Prof. Gardiner, 1 have been able to examine an example 

 of this genus from the Indian Ocean. The specimen is unfortu- 

 nately immature, but, as might have been expected, the photo- 

 phores were not found to differ in any esseiitial feature from 

 those occurring in the closely related form AcavtJiephyra dehilis. 

 Although the simpler organs are by no means so numerous as in 

 that species, all tho.se of a more complex character are present 

 and occur in the usual positions on the pleopods and uropods, and 

 behind the base of the last pair of legs. 



Coutiere mentions that in his specimen of /Inplophorus, " con- 

 sei've dans la glycerine formolee," the luminous organs are slightly 

 yellowish ; in the examjile from the Indian Ocean, which was 

 preserved in spiiit, no trace of pigment remains. The photo- 

 phores are, however, so completely identical in structure with 

 those occurring in Acanthephyra, that, notwithstanding the fact 

 that the blue coloration h.is never been seen in JlopJophorus, 

 there can be little doubt that such a pigment really exi.sts in 

 living .specimens. 



Whether the organs occur in all the species or whether, as in 

 the case of Sergestes and Acanthephi/ra, they exist only in a 

 limited number, must be left to future investigators. 



The PiGMENTATlO.V OF THE PhoTOPUORES. 



It has already been mentioned that a deep blue pigment i.s, in 

 life, a.ssociated with the photophores of Decapoda, occurring in 



* For the order iti which thesp orfrHiis arisp nnd thpir numher in sppcinipns of 

 different ape, v. Coutiere, loc. cit. lOOfi, hikI Kfinp, Fisheries. Inland. Sti. Invest., 

 1908, I. [lOlOj. 



