32 T. NISHIEAWâ. 



patch, at about half mile west of Masaki Island. It was deep brownish- 

 yellow in color, and was 3 or 4 feet beneath the surface, formin«,' ir- 

 regular cloud-like masses, interspersed with the water of the ordinary 

 color. The thickness of the discolored patch was 2 — 4 feet. 



On taking a little of it into a glass-cup, it was observed that an 

 enormous number of minute organisms swarmed in the water which was 

 as clear as usual. There could be no question, that the discoloration 

 of the water was due to the presence of numerous minute organisms. 

 On examination with a microscope, it was found that the organism 

 belonged to the Peridiniaceae. It has a polygonal shape, with an 

 areolated shell. The anterior pole is pointed, and there are two proces- 

 ses, one larger than the other, on the posterior pole. The longitudinal 

 groove is very broad in its posterior part having a conspicuous " G-eis- 

 sel-spalte", from which a long flagellum extends backward. Anteriorly 

 the groove becomes very narrow and scarecely communicates with the 

 polar opening. The left end of transverse groove in the ventral side is 

 below the right. The chromatophores are small and numerous, brownish- 

 yellow in color. The length of the body is 0.04b' mm. and the larger 

 process is 0. 0062 mm. long. The organism moves very actively by 

 rolling itself on the longitudinal axis of the body. Sometimes two 

 individuals were connected in a chain like Ceratinm tripos. 



The organism occurred in such a great abundance that it gave to 

 the water very noticeable color and peculiar odor, 800 or even nearly 

 3,000 in the densest part, having been estimated to be present in a drop 

 of the discolored water. George Murray Esq. of the British Museum, 

 to whom the specimens were sent, has kindly identified the organism. 

 It is Gonyaulax pol y gramma Stein. According to his statements, it is 

 widely distributed ; he has found it frequently in the tow-nettings from the 

 Atlantic, but he has never before seen it in such an abundance. 



When disturbed, the active Gonyaulax gives a very beautiful 

 phospholescent light in the dark. By keeping the discolored water 

 in a glass bottle, the minute organisms gather near the surface of the 

 water. After a short time, some of them sink to the bottom and the 



