Y. HANEDA 347 



The two above-mentioned species of Pyrosoma are brilliantly lumi- 

 nous when stimulated. The species of Salpa are not luminous under 

 natural conditions. They emit light only on strong stimulation, such 

 as cutting or tearing the body. As the luminous regions were small and 

 the periods of luminosity very short, I could not determine the posi- 

 tion of the luminous organs. 



Annelida 



Polychaeta 



There are many species of luminous Polychaeta in Japan. However, 

 no reference to their luminosity has appeared except in Chaetopterus 

 variopedatus and Mesochaetopterus japonicus Fujiwara ( 1935 ) . Chae- 

 topterus variopedatus, which appears to be a species of worldwide 

 distribution, is found on the sandy bottom of Japanese waters and also 

 along the west coast of Korea. Fujiwara (1935) described somewhat 

 difiFerent light regions occurring in the Mesochaetopterus japonicus of 

 western Japan. 



During my stay in Palao, I collected some species of luminous 

 Polychaeta. Among them Onuphis sp. and Stylarioides parmatus 

 Grube (1878), both identified by Mr. K. Takahashi, are the most 

 interesting species. Onuphis sp., belonging to the family Eunicidae, 

 lives in coral in the neighborhood of the Palao Tropical Biological 

 Station, Corror Island, Palao. This Polychaete, a beautiful pink in 

 color, with brown stripes, is 234 mm long, 5 mm wide, and has 204 

 segments. The pairs of luminous spots are arranged from the first 

 setigerous segment to the last on the abdominal lateral margin of 

 each segment. The animal emits a bluish green hght when stimulated, 

 but it does not discharge a luminous slime. It is closely related to 

 the species of Onuphis investigatoris Fauvel from the Arabian Sea, 

 the luminosity of which is unknown. 



A single specimen of Stylarioides parmatus was collected from the 

 coral reef of the Corror Island, Palao. It lives in a tube 20 mm long 

 and 2 mm in diameter, which is attached to a dead shell. Its cephalic 

 plate becomes luminous when irritated, emitting a yellowish green 

 light. No luminous slime is discharged. This species occurs in the 

 Philippines, Ceylon, Madras, Madagascar, and New Zealand, but its 

 luminosity has never been reported. 



