354 LUMINOUS ORGANISMS OF FAR EAST 



(1913), Harvey (1917), Shoji (1919), Y. K. Okada (1933), and 

 Hasama ( 1941 ) . However, the second group has not been investigated 

 until recently. 



Squid associated with luminous bacteria were studied by Dr. T. 

 Kishitani. He reported that myopsid squid, such as Loligo edulis, 

 Sepiola birostrata, and Euprymna morsel, are luminous species pos- 

 sessing symbiotic luminous bacteria. All live in shallow water. Their 

 luminous organs have openings to the exterior, and luminous bacteria 

 live symbiotically in the ducts. In Singapore in 1944 I collected and 

 observed another species of myopsid squid having luminous bacteria. 



Regarding the second group, I recently caught in a trawl net at 

 Suruga Bay a luminous squid producing an abundant luminous secre- 

 tion. The scientific name of this squid is Stoloteuthis leucoptera Ver- 

 rill, identified by Dr. Y. Okada, and is a species closely related to 

 Heteroteiithis. As shown in Fig. 6, its mantle is 20 to 30 mm long, 

 with a large white band that has been mistaken by some observers 

 for a luminous skin organ. The round white luminous organ is situated 

 on the ink sac and is connected to the exterior by two pores. A sec- 

 tion of the luminous organ is similar to that of Heteroteiithis, which 

 also produces a luminous secretion. 



Stoloteuthis is not luminous when freely swimming, but, if touched, 

 will spurt through the funnel a beautiful bright bluish secretion like 

 that of the mollusc Pholas. This luminous secretion comes out of the 

 pores of the luminous organ. I have endeavored to cultivate luminous 

 bacteria from the luminous organ and the luminous secretion, but all 

 the results were negative. As this luminous squid is comparatively 

 easy to catch in trawl nets at Suruga Bay, I intend to study it in 

 detail in the future. 



The third group of squid with well-developed photophores have 

 been studied by many workers in Japan. Among many deep sea lumi- 

 nous oegopsid squids, Watasenia scintiUans is most famous and re- 

 markable. Watasenia scintillans (Japanese name, Hotaru-Ika, mean- 

 ing firefly squid) comes to the surface in Toyama Bay, on the coast 

 of the Nippon Sea, each year during late April to mid-June, to breed. 

 This species is caught and dried on the beach in the sun for food 

 and is an important commercial product of Uozu and Namerikawa, 

 towns on Toyama Bay that are the best locations for collecting. 



