442 DR. J. S. BOWERBANK ON THE SPONGILLID^. [NoV. 24, 



it has hitherto been very difficult to distinguish one species from the 

 other. 



These pecuharities in the structure of the ovaria of the two species 

 have a more extended value than that of merely serving to establish 

 a specific difference, inasmuch as the subsequent examination of the 

 different species of Spongilla that have come into my possession has 

 convinced me that S.Jluviatilis and IS. lacustris may through their 

 aid be considered as the types of two well-defined groups, which are 

 distinguished by modifications of these peculiarities in the structure 

 of each of their ovaria. 



The two British Spongillas appear to have long since been found, 

 and described under various names, in several parts of the continent 

 of Europe ; but no other species were known to naturalists until, in 

 1849, Mr. Carter named and described five new ones in his " De- 

 scriptive Account of Freshwater Sponges in the Island of Bombay," 

 published in the ' Transactions of the Bombay Branch of the Royal 

 Asiatic Society' (No. 12, 1849); and one other species I received 

 from my friend Mr. Dean, of Clapham ; it was brought by Dr. 

 Bradley from the freshwater tanks near Aurungabad, in the domi- 

 nions of the Nizam, thus making six from the East Indies. The 

 whole of these agree, in their general habits and in the fragility and 

 delicacy of their structure when dried, with our British species S. 

 Jluviatilis and S. lacustris. I am much indebted to Mr. Carter for 

 his kindness and liberality in presenting me with specimens of the 

 species he has so ably investigated and described, by which I have 

 been enabled to compare them carefully with our European ones ; 

 and to one or the other of the two groups represented by these spe- 

 cies the whole of the East Indian ones may be referred. 



During the course of my examinations of the East Indian species, 

 I received two consignments of Spongillas from the River Amazon, 

 collected by Mr. Bates, the indefatigable and talented investigator 

 of the natural history of those interesting regions. In these two 

 collections I have been able to distinguish as many as six new spe- 

 cies ; to which may be added a seventh from the River Winguay, a 

 tributary to the Amazon, presented to the Royal College of Surgeons 

 by W. Bragge, Esq. The greater portion of these species differ 

 widely in their general habits from the European and East Indian 

 ones, being exceedingly strong and rigid in their dried condition, and 

 the reticulations of their skeletons are very much stouter and 

 stronger ; but although thus differing, the whole of them may be 

 referred to the group represented by our British species S.Jluvia- 

 tilis, having the ovaria furnished with birotulate or scutulate spicula. 



In the seven species which I have described from the River Ama- 

 zon there is an amount of variation in the forms and proportions of 

 the birotulate spicula that renders these organs peculiarly valuable 

 as distinctive characters. Thus, in 5. Meyeni the birotulate forms 

 do not differ very much from those of -S. Jluviatilis, but their pro- 

 portions are three or four times as great as in that species. In S. 

 plumosa the size of the rotulse very little exceed those of S.Jluvia- 

 tilis, but the length of the spicula are at least five times that of the 



