

172 Miscellaneous . 



" second bottoms " then, said to be only reached to any considerable 

 depth by the annual floods occurring during parts of May and June, 

 and not to continue flooded more than six weeks at a time, the 

 screw-bean abounds. It is described as a small tree of the general 

 appearance of a peach-tree, but with more slender drooping branches. 

 More or less of an alkaline deposit whitens the ground upon which 

 they grow, and the approaching traveller is puzzled to see in strong 

 contrast with it hundreds, or even thousands, of dark masses, " like 

 wasps' nests," suspended two or three feet above. 



It was this conuudriim that confronted Dr. Palmer during his 

 recent visit, and the answer we have is in the sponge before us. 

 From the Amazon River in the tropics to the waters of Maine and 

 Nova Scotia in the temperate regions of the north sponges have 

 long been known to afi'ect the pendent branches of stream-bordering 

 bushes ; but it is unlikely that they have ever before been observed 

 in such quantities suspended for nine or ten months of the year over 

 land parched and desolate. 



On referring to Mr. Carter's earlier descriptions of his discoveries, 

 we find that, though he collected this species on two or more occa- 

 sions, the fragments were always found detached from their place of 

 growth and floating upon the surface in the water-tanks referred to 

 about one month after the rainy season had commenced. He be- 

 lieved that the vitality of the gemmules was preserved during the 

 dry season notwithstanding their exposure to the sun and desic- 

 cating winds, and that their germination after the water had again 

 reached them was followed by a very rapid growth of new sponge. 

 This would seem to have been the case also with the present variety, 

 as, according to the reports of the collector, the masses could not 

 have been submerged for a greater period than six weeks in any one 

 year. Whether the whole bulk as now seen was attained during a 

 single season or is the cumulative result of several annual growths 

 of the persistent masses cannot now be determined. 



It is worthj' of notice that M. plumosa and this variety, v. Pahneri, 

 difi"er from all other known freshwater sponges by the presence in 

 them of a compound or substellate dermal spicule. The spicules of 

 the dermis throughout the group are generally minute spined ace- 

 rates ; in M, Everetti, Mills, we find them as minute birotulates. 

 In this species the two forms seem to be combined ; the spines have 

 become central and prolonged, while their capitate extremities 

 suggest the rotules of the last-named species. 



Of the six sponge-masses from the above locality, sent by the 

 Smithsonian Institution for examination, the smallest was somewhat 

 fusiform in shape, and proved to belong to a different species — Mey- 

 enia crateriformis, Potts — heretofore found along the eastern border 

 of the United States. In it alone the mass was not darkened by 

 the presence of some pervading vegetable parasite. — Proc. U. S. Nat. 

 Mus. 1885, p. 587. 



