102 



S. aspinosa, Potts. Monograph, p. 184. 



One specimen, locality Absecum Creek, N. Jersey. 



S. fra^ilis, Leidy. Monograph, 197. 



There are numerous characteristic specimens from different 

 localities, as the species is every where in North America. 1 

 have not specially described each. It is very abundant about 

 Buffalo. It may be of interest to note that it was the first 

 North American sponge described (1851) and the second found 

 in the Niagara, at least so far as the record of the local societies 

 attest (October 1879). Certainly none awakened any greater 

 interest and enthusiasm than the beautiful crusts of gemmules 

 found on stones of the pier at Black Rock. Strangely enough 

 this same form seems to have kindled the fire in the mind of 

 Mr. Potts. In the Monograph p. 199 he says, "In 1878 or 1879 

 my attention was first attracted to the subject of fresh-water 

 sponges by the discovery of a few gemmules, resembling a 

 rust colored incrustation upon a stone from Lansdowne run, 

 Philadelphia." A trivial circumstance surely, but one that 

 led to researches that advanced science and soon demonstrated 

 the wonderful richness of this type of life in America as 

 compared with the scientifically explored parts of the old 

 world. 



Among the specimens of this species are several marked 

 "compound form." They differ from the ordinary form which 

 has a layer of close-set statoblasts or possibly seven successive 

 layers, representing growth during as many years, the sarcode 

 and spicules dropping away each fall. In this variety the gem- 

 mules occur in groups of two, three, four or more, bound together 

 by a compact "cellular crust," often conspicuous; the forami- 

 nal tubes protrude slightly from the periphery. These masses 

 are held loosely in the substance of the sponge, often surmount- 

 ing a layer of ordinary forms cemented firmly to the support. 

 Examples growing on weeds are wholly of the compound 

 variety. Mr. Potts has made the reasonable suggestion that 

 the normal type, cemented firmly to permanent supports, mam- 

 tains the species from year to year m the same place ; the 

 other is dispersed on the breaking up of the sarcode, thus dis- 

 tributing the same. 



MEYENIA. 



M. fluviatitis. Monograph, p. 219. 



This is one of a few .species occurring in the greatest abun- 

 dance about the Niagara and its tributaries. Those from the 

 river generally agree very well with the type whilst those from 

 ponds and streams show much variation. The variations con- 

 sist in smooth or niicro-spined spicviles, thicker "ccust" in the 



