454 Mr. H. J. Carter on a 



nized his variety ; that Mr. Mills's specimen which had come 

 from England came from himself; and that he would be very 

 glad, not knowing much about sponges, if I would publish 

 a description of it. 



It then struck me that the label " Ditchley's " being on 

 both Mr. Waller's and Mr. Mills's preparations, there must 

 be some connexion between the two, so I immediately (that 

 is on the 28th March last) communicated the facts to Mr. 

 Waller, who, in reply, not only pointed out the way in which 

 the " Ditchley's " specimen got to America, but very kindly 

 sent me a specimen of it in the natural but dried state, which, 

 by the presence of the immature statoblasts &c, exactly 

 corresponded with Mr. Mills's preparation. To this speci- 

 men Mr. Waller added the following statement, viz. : — that 

 the sponge, growing around the stems of an aquatic plant, 

 had been obtained from a large pond at " Ditchley's Manor," 

 South Weald, near Brentwood, in the county of Essex, and 

 had been noticed by him as a variety, in a paper entitled 

 " Variation in Spongilla fluviatilis" published in the ' Pro- 

 ceedings of the Quekett Microscopical Club, vol. v. 1878. 



As Kir. Thomas's specimen of this sponge from the Calumet 

 river is very small in quantity, I must describe it chiefly 

 from what Mr. Waller has kindly sent me, thus : — 



Meyenia jiuviatilis, var. angustibirotidata. 



Coating the stems of aquatic plants to the extent of one 

 sixth of an inch in thickness all round. Consistence elastic, 

 fragile. Colour light yellow-brown. Skeletal spicule smooth, 

 curved, fusiform, gradually sharp-pointed, varying in size 

 under 75 by 3-6000ths in. in its greatest dimensions. 



Statoblast globular, even on the surface, and white in 

 colour when fully developed, infundibularly depressed over 

 the hilous opening of the chitinous coat ; about 85-G000ths 

 in. in diameter ; consisting of the usual germinal contents, 

 surrounded by a layer of birotules in juxtaposition, arranged 

 perpendicularly over the chitinous coat, and filled in between 

 with a microcell-structure up to the umbos of the birotules, 

 which, being naked and allowing the light to pass through 

 them, present a dark point respectively like minute holes in 

 the midst of the wdiite microcell-substance ; birotule consisting 

 of a cylindrical shaft, more or less constricted in the middle, 

 which is sometimes furnished with one or more spines ; rotule 

 fringed towards the margin rather than denticulated, so as to 

 present a striated appearance, which does not reach the umbo 

 or centre ; total length of birotule about 6-6000ths in. 



Loc. England and America. 



