334 SCYPHO-MEDUSyE. 



tentacles, uppermost in depths of from one to tliree feet of water. 

 I was struck by the handsome mass of arborescent tentacles which 

 they disjjlayed, and by the peculiarity of their lying upside-down. 

 The dark mud which formed the bottom of the swamp was com- 

 posed of decayed vegetable matter, confervoid growths, diatoms, 

 and a few infusoria : but when I raised up these Medusae, I found 

 underneath each a ]jatch of white sand corresponding with the out- 

 line of the organism, but completely concealed by the umbrella when 

 the Medusa lay in its usual position. Tho sand was derived from 

 corals, shells, and the volcanic rocks of the island ; and the light 

 l)atches formed a marked contrast with the dark mud around. I 

 was unable to Hud any satisfactary explanation of these curious 

 patches of sand ; and I, therefore, proceeded to interrogate the 

 Medusae on the subject by watching them, but to no purpose. So I 

 had my revenge by turning them all over on their tentacle's, when 

 each one immediately began to contract its umbrella in a most 

 methodical fashion, and, after swimming a short distance, deliber- 

 ately resumed its former position of tentacles upward. I had an 

 extensive experience of mangrove-swamps after we left Simbo ; 

 but these self-willed Medusae never came under my notice again.^ 



With regard to these Medusae, I should remark that they belong 

 to a species of Polyclonia, and are classed amongst the Scyplio- 

 Medusae.^ Two species of Polyclonia seem to be known, P. frondosa 

 (Agassiz) and P. Mertensii (Brandt), the first found in the Florida 

 seas, and the latter in the Carolines. I am inclined to think that 

 the Solomon Island species is more nearly allied to P. Mertensii. 

 Both species, however, have similar habits, lying on the mud of 

 mangrove-swamps, with their tentacles uppermost. 



The singular habits of these Scypho-Medusae were noticed by 

 Brandt in 1838. They have since been remarked by Mosely^ in 

 the Philippines, and by Archer* in the West Indies. L. Agassiz in 

 his " Contributions to the Natural History of the United States," 

 describes and figures the Florida species {Polyclonia frondosa) ; and 



1 I referred to the habits of these Medusae in "Nature," Nov. 9th, 1882. 



- I compared my notes with thgi, description and figures given by Agassiz in his " Contrib. 

 Nat. Ilist. U.S.A." (18C2 : vols. iii. and iv.). In tlie Solomon Island species, the dendriform 

 mass resolves itself into 8 principal branches, each ramose, and all united at their bases by 

 a common membrane. The umbrella, which was finely lobed or crenulated at its margin, 

 displayed about 40 radiating canals, each co.mmunicating by an anastomosing network with 

 the canal on cither side of it. 



» Mosely's " Ndtes by a Naturalist," p. 404. 



*" Nature "Aug. 4th, 1881. 



