LIMNOCODIUM IN THE UNITED STATES. 305 



of the present case thus closed, the details, so far as known, may 

 properly be formulated and made available. 



Locality. 



The medusae were discovered in the aquarium of Mr. W. B. 

 Shaw, a florist, who for many years has cultivated various aquatic 

 plants, among them several species of tropical, or subtropical 

 water lilies, Nymphoea zanzibarensis, Cabomba ( Caroliniana ?), 

 and a species of Ludwigia. But, all these were reared from seeds, 

 no grown plants having been at any time imported or introduced 

 into the tanks. And at no time has the Victoria regia been grown 

 here, a fact of no small interest in relation to earlier suggestions 

 as to the problem of the transportation of the medusae from 

 tropical waters. 



The hot-house contained in all six tanks, each three feet wide, 

 three feet deep, and about twelve feet long. These were all 

 stocked in the same way, and with about the same sorts of 

 plants, and a species of Paradise fish. The aquaria are of the 

 balanced sort, and have been in use for some six or eight years 

 without material change of water or organisms. The aquaria 

 are used chiefly during the winter by Mr. Shaw including late 

 fall and spring, for the purpose of carrying over certain of the 

 more delicate tropical plants from season to season, and stand 

 idle during summer, water being added to replace the loss due 

 to evaporation. 



Of these six tanks, alike in construction, water supply, and 

 other features, medusae appeared in one only, and that about mid- 

 summer, flourishing during the hot weather and promptly disap- 

 pearing with the approach of autumn cold. When first discovered 

 they were in considerable numbers and of various sizes "some 

 as small as a pin's head and some one fourth inch in diameter." 

 The largest specimen which came to my hands measured about 

 9 mm. in diameter by 4 mm. in height of bell. 



Hoping to obtain some clue as to the hydroid stage I obtained 

 through the courtesy of the Bureau of Fisheries a collection of 

 various plants growing in the tank, with scrapings of algal slime 

 and other debris from the sides and bottom of the tank. This 

 was promptly and carefully examined on arrival, and frequently 



