256 PROCEEDINGS OF THE ACADEMY OF [1887. 



as a variety of that species. Upon the slender stem that supports it 

 however, on the two leaves pertaining to that stem and even parasit- 

 ical amongst the spicules of the primary sponge, I discovered several 

 other kinds ; viz. on the stem, little groups of Meyenia gregaria 

 almost exactly as Dr. Bowerbank has described them; on the 

 leaves, Spongilla navicella, Carter, whose enigmatical character has 

 been alluded to in the remarks on that species ; also a curiously 

 minute new species now described under the name of Meyenia 

 minuta ; and upon or within the sponge itself, a few gemmules of 

 Ttibella recurvata and many of a new species of Parmula, that will 

 be presently noticed : six species belonging to four genera; with dis- 

 tinct but insufficient indications of one or two others. With a 

 productiveness and withal a variety so great as this, it may not be 

 cause of wonderment that the writer should feel that were the op- 

 portunity afforded thoroughly to examine a single log, that had 

 floated for a year in one of the side channels of the Amazon, the 

 history and classification of fresh-water sponges in America might 

 have to be in large measure rewritten. 



KEY TO THE SPECIES OF THE GENUS PARMULA. 



1. Sponge rigid, coarsely reticulated. Gemmule surrounded by a 

 tuberculated parenchyma, charged with parmuliform spicules, 

 both upon the chitinous coat and on the outer surface of the 

 tubercules, in which they are associated with a minute spined 

 acerate. F. batesii. 



2. Sponge rigid, coarsely reticulated. Crust of gemmules gran- 

 ular, ^penetrating the compact spicular capsule by many slender 

 processes. No outer series of parmuliform spicules. 



P. hrownii. 



3. Sponge minute ; skeleton spicules not fasciculated. Crust of 

 large granuliferous cells forming irregular rounded lobes whose 

 size and shape are determined by the interspaces of the spicules 

 of a much less compact capsule. No spined acerates. Parmu- 

 liform spicules forming a complete armature upon the chitinous 

 coat. P. riishyi. 



The descriptions of the older species are copied from H. J. Charter, 

 preferred to those of Dr. Bowerbank as showing the results of a 

 later study of the specimens and one made in the light of the re- 

 vised classification ; yet in the course of my study of the same spe- 

 cies I have been delighted with the minute accuracy of Dr. Bower- 

 bank's observations, particularly those included in his general re- 

 marks. 



