1863.] DR. J. S. BOWERBANK ON THE SPONGILLIDiE. 443 



British type of the group. In S. paulula there is a tendency in the 

 proximal rotulse of the spicula of the ovaries to become obsolete, 

 few of them exceeding half the diameter of the distal rotulse. In 

 S. reticulata the proximal rotulse are still less in their proportions ; 

 and in S. recurimta this part of the spiculuni is represented by a 

 slight spherical head, like that of a common pin. In S. Brownii and 

 S. Batesi the shaft as well as the proximal end of the birotulate spi- 

 culum becomes entirely obsolete, and we have One rotula only left ; 

 the birotulate spiculum being thus represented by the scutulate forms 

 of those species. 



I have received five species from North America, including one 

 from Vancouver's Island. The whole of these resemble, in their 

 habits and in the fragility of their structures, the East Indian and 

 British species. Two of them belong to the rotulate group, and 

 three to the elongo-spiculate one. These five, I apprehend, are but 

 a small portion of the number of species that we may expect to find 

 in the lakes and rivers of North America. 



In a letter from the late Professor Bailey, of West Point, New 

 York, in reply to my inquiries regarding the Spongillidce of America, 

 he writes, " I have been greatly disappointed by not finding any 

 specimens of American Spongilla. I felt quite sure that I had a 

 large piece, which I gathered in Lake Monroe, Florida, having 

 abundance of gemmules ; but the most careful search among my 

 Florida gatherings fails to bring it to light. It must have been a 

 portion of this which I sent to Mr. Marshall ; perhaps I sent him 

 the whole, although that is not my usual custom. I send a speci- 

 men of the mud of a creek in Florida, containing spicules and 

 Amphidisci from the same species as that above referred to. The 

 Florida Spongilla grew abundantly on the submerged roots of the 

 deciduous Cypress. I ought to have collected fine specimens of 

 Spongilla in Maine two years ago. The river in which I looked 

 daily, when there, abounded in Spongilla, which covered logs, roots, 

 stems, &c., with masses often of several feet in extent. It generally 

 was in a layer of from about a quarter to half an inch in thickness, 

 of a fine Oscillatoria-green colour, and occasionally rising into finger- 

 like processes of several inches in length. 



" The Spongilla of the small lakes in this vicinity rarely forms 

 very large masses. I have found it in layers on the undersides of 

 stones in moderately deep water, and have also seen finger-like masses 

 in shallow water." 



In the dust from the box containing the fragments of Spongilla 

 from the water-pipes of Boston, sent to me by Dr. Asa Gray, there 

 were spicula which indicate the existence of two or three other spe- 

 cies in the waters that supply the inhabitants of Boston. One is an 

 acerate spiculum, as large as a full-grown one, from the skeleton of 

 the Spongilla from the water-pipes, S. paupercula, but not smooth 

 Uke that spiculum ; on the contrary, it is abundantly furnished with 

 incipient spines, which cover all parts of the shaft, excepting near 

 the apices, where it is smooth for the space of about twice the 

 largest diameter of the shaft. Spongilla cinerea, Carter, from 



