1 907] Records of the Indian Museum. 259 



Hexactinellidce. 

 Aphrocallistes beatrix. 



Alcyonaria. 

 Pennatula pendula. 



Station 375, off Dondra Head, Ceylon, 605 fathoms. 



Fish. 

 Lamprogranimus niger. 



Crustacea. 



Heterocarpus alphonsi. 

 Polycheles phosphorus, 

 Nematocarcinus gracilis. 



Mollusca. 



Pleurotoma symbiotes with its symbiotic Epizoanthu? 

 A small species of Dentalium. 



Aster ids. 



A species of Hymenaster. 



Among these twenty-four species only three showed phospho- 

 rescence. These were the prawns Heterocarpus alphonsi and Pan- 

 dalus alcocki, and the A^cyonarian Pennatula pendula. Of these 

 the Heterocarpus gave the most striking display of its illuminating 

 powers, which have been already noted by a former " Investigator " 

 naturalist (Alcock, Ann. Mag. Nat. Hist., vol. viii, i8gi, page t6). 

 We, too, were able to observe all that this author described. While 

 the prawn was in water the light floated away from its oral region 

 in two streams which became extinguished about two inches from 

 their source. 



The property which the secretion has of retaining its illumi- 

 nating power after leaving the body was well illustrated by the 

 following occurrence : When the prawn was taken out of the 

 bucket, the water, dripping from the animal, was so highly lu- 

 minous that a bright phosphorescent stream flowed down the 

 antennae (which were five inches long) and dripped from their 

 ends in globules of light that did not become extinguished until 

 they intermingled with the water in the bucket. 



The other prawn which showed the same powers, but to a 

 rather less marked extent, was one of the five specimens of Pandalus 

 alcocki. The other four, whose tissues must have been quite dead, 

 showed no light. This proves that negative evidence is of no 

 value in such observations. 



