32 INLAND FISHERIES. 



afterwards, hardly a live crab or shrimp could be found. Along 

 the shores, however, in the same vicinity, cartloads of dead shrimp 

 were piled up in windrows, and among them were strewn great 

 numbers of crabs and fish of various kinds, especially menhaden 

 and eels. This singular behavior and alarming mortality of ma- 

 rine animals was reported from nearly every station at which the 

 red water occurred, and from no other station, wdiich indicates 

 that the two phenomena are related as cause and eft'ect. 



It was commonly believed that dye-stuffs or other refuse emptied 

 into the rivers at the upper part of the bay gave to the water its 

 color and unpleasant odor, but microscopic examination showed 

 that the water was swarming with minute organisms, species of 

 Peridinmm. The Peridinium is reddish brown in color and oc- 

 curred in such excessive abundance that it gave to the water its 

 peculiar color and odor, besides making it so opaque that one 

 could hardly see a white shell six inches below the surface. 



With regard to the systematic position of this organism there is 

 a difference of opinion. It is, in fact, ranked with the animals by 

 some authors, and with the plants by others. I have not yet been 

 able to determine the species of our Per'id'imnin. It resembles in 

 many respects Carter's Peridinium sanguhiemn ; it is much flat- 

 tened, and the anterior end is distinctly bilobed, like Peridhuum. 

 tahuhUwa, though the lobes are more rounded. Besides a flagel- 

 lum extending forward from the ventral groove, a very large 

 flagellum lies in the equatorial sulcus and entirely encircles the 

 body. No cilia could be demonstrated. 



After September 9th and lOtli, when the great mortality of fish 

 occurred, the Peridinium became, for a few days, less abundant, 

 and then increased again until the 23d. There was a heavy rain 

 on the 23d, and on the following day the water was comparatively 

 clear. Since this date it has been more or less in evidence up to 

 the day of writing (October 7th). On September 21st the number 

 of Peridinium per cubic centimeter in the Seekonk river was esti- 

 mated at 5,880. This was enough to give the water a very notice- 

 able red color. Nevertheless, the marine animals appear not to 



