101 



Key to Genera. 



1. Statoblasts or gemmules surrounded by smooth or 

 spined acerate or cylindrical spicules only. Spongilla. 



2. Statoblast surrounded by equally birotulate spicules, 

 all of one type, resting by one rotula on the chitinous coat. 



Meycuia. 



3. vSame with birotulates of hvo types, /. <^. , at least shafts 

 of unequal length. Heteronicyenia. 



4. Same as Meycuia except the birotulates have unequal 

 rotulae, the larger resting on the chitinous coat. Tubella. 



5. Same as preceeding genera except the foramen is a 

 prolonged tube with its distal extremity expanded into a more 

 or less funnel-like expansion bearing one or more cirrous appen- 

 dages on its margin. Carteriiis. 



SPONGILLA. 



I. S. lacustris, Linn. Monograph*, p. 186. 



This exceedingly variable and widely distributed species ap- 

 pear to be found but sparingly at Buffalo. It should be 

 looked for in shallows along the Niagara and other streams, 

 even where there is considerable flow. It also occurs in ponds 

 and has the habit, unlike most species, of growing fully exposed 

 to the sun's rays, upon suitable supports or even upon the bot- 

 tom sending its long bristling fingers up into the passing water. 

 In such situations it is usually green and easily overlooked 

 among aquatic vegetation. 



The specunens are as follows: i. Mass of branches, 5^x3^x2', 

 green. Fox Lake, Wisconsin, Sept. 1886. Collector Henry 

 Mills. 2. Similar branches. Fox River. Same date. 3. Speci- 

 men incrusting twigs, colorless. Bear Creek, Iowa Sept. 1883 

 Henry Mills. 



There are also two varieties of S. lacustris represented, viz: 

 paupercula, Bk. A small quantity from Cochituate Lake, 

 Boston, and mtitica, Potts, described from an ordinaiy ex- 

 ample of lacustris in which the crust and gemmule spicules 

 are wanting. From Edward Potts. Locality Philadelphia. 



*Monograph Fresh-Water Spongesby Edward Potts, reprinted 

 from Proc. Phila. Acad. Nat. Sci. 18S7. This admirable 

 treatise must necessarily^ afford the basis for all future work 

 on American fresh water sponges. 



