1G2 



The Microscope. 



There are now four, if not five, species in the genus with some 

 varietal forms not yet determined, none of which were known eight 

 years ago. It should be stated that the peculiarities which distin- 

 guish the fresh-water sponges fi-om some of the marine species, is the 

 presence in the former of small, seed -like bodies, visible to the 

 unassisted eye. These are a kind of winter-egg, or resting-spore for 

 the preservation of the species during the changes incident to fresh 

 water in winter. These bodies are now called statoblasts, {formerly 



gemmulae,) in keeping with the 

 name given to bodies of a similar 

 character found in the fresh-water 

 polyzod. The points of distinc- 

 tion between the genus Carterius 

 and the sponges of other genera, 

 consist in the presence of certain 

 cirrous appendages, attached in 

 various forms to the foramenina 

 of the statoblasts of the genus, as 

 now to be described. 



Carterius tiibisperma Mills : 

 has a tubular process extending 

 from the foramen of the statoblast, 

 and varying somewhat in length, 

 but generally as long as one 

 diameter of the globular body. 

 To this tube are appended several 

 tendril-like or cirrous processes. 



Diagrammatic view of statobla'=;t — 



Carterius tubisperma Mills : c. globular also Varying in length, and ending 



body in section, surrounded by birotulate ^ o o o 



spicula, one end of which rests on the clii- 



tinous coat d; b, tube of statoblast, which 



is a continuation of d; a. cirrous process 



too hastily drawn; e, delicate placenta-like 



membrane, holding tae germinal cells, 



which, when mature, and under suitable 



conditions, af^e supposed to escape at /, 



pass up the tube, making their exit at the 



end g. 



sometimes in a poorly -defined, or 

 rudimeotary hook. I have found 

 specimens of this sponge as large 

 as one's hand, and have supplied 

 them to the British and Liverpool 

 museums, to Austria, and the National museum at Washington, D. C. 

 Carterius tenosperma Potts, has long tendril-like processes 

 extending from the foramen of the statoblast to nearly six inches in 

 length. These are frequently so knotted, and tangled together, that 

 it is difficult to separate them, their purpose being, one might 

 naturally conclude, to hold the mass of sponge from being scattei'ed 

 by freshets or other causes. 



Carterius latitenta Potts, is a sponge of similar character to the 

 two foregoing, but it has wide, almost ribbon-like processes, (some- 



