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



Bombay, has the skeleton- spicula incipiently spinous, but I have not 

 hitherto found the same character in any of the North American 

 species. These spinous spicula apparently represent a species at 

 present unknown to us. Beside the spinous spiculum described 

 above, there are two other forms, neither of which are above one- 

 fifth or one-sixth the length of the skeleton-spiculum of S. pauper- 

 cula ; and both have every character of being tension-spicula, or those 

 belonging to the interstitial and dermal membranes of some species 

 of Spongilla. One of these is cylindrical, straight, short, and stout, 

 with hemispherical apices, and is covered all over with incipient 

 spines, which requires a linear power of about 300 to define them 

 well. The other is of about the same length as the one last de- 

 scribed, but of a fusiformi-acerate shape, is very slender, and requires 

 a power of about 700 linear to define it well. It is entirely covered 

 with well-produced conical spines, with a few truncated ones near 

 the middle of the shaft. This spiculum is very like that which 

 abounds in the dermal membrane of Spongilla lacttstris ; but it is 

 most probable that it may be an incompletely developed one of S. 

 haileyi. 



In Spongilla lacustris the tension-spicula of the membranes and 

 the dermal spicula of the ovaria differ in form. The former are 

 fusiformi-acerate, covered with spines ; the latter cylindrical and 

 very much curved; so that, judging from these circumstances, it 

 may ultimately prove that the two small forms of spicula from the 

 dust accompanying S. paupercula may belong to the same sponge, 

 or it may be that they indicate the existence of two distinct species. 

 In the latter case, there are evidently three distinct species of Spon- 

 gilla in the sources of the Boston water beside the one prevailing in 

 the water-pipes. 



At the time I received the specimen of Spongilla from Professor 

 Bailey to which I subsequently attached his name, he very kindly 

 sent me a small packet of infusorial earth, very rich in the spicula 

 of the Spongillidce, " from Duval's Creek, near Lake Monroe, St. 

 John's River, Florida." I have examined this material carefully, 

 with the view of forming an approximate estimate of the number of 

 species of Spongilla existing in the waters whence it came ; and the 

 following are the results. I found the birotulate spicula of the 

 ovaria of S. Baileyi in moderate abundance, but I did not recognize 

 those of the membranes. A second form of birotulate spiculum, 

 with a strongly spiculated shaft, occurred in abundance. This spi- 

 culum is very like those of the ovaries of S. Meyeni, Carter, from 

 the water-tanks of Bombay, and could not by its form alone be 

 separated from those of that species. Beside these there are a con- 

 siderable variety in size and form of smooth spicula, which have 

 every appearance of being skeleton-ones ; so that the number and 

 variety of these justify the idea, eliminated by the number and va- 

 riety of tension-spicula of unknown species, that there are at least 

 five or six North American species of Spongilla beside those with 

 which I am already acquainted. 



The Australian species S. Capewelli is an interesting addition to 



