10 U.S. NATIONAL MUSEUM BULLETIN 272 



Euspongilla lacustris var. macrotheca Vejdovsky, 1883, p. 18. 



Spongilla lacustris var. dawsoni MacKay, 1885, p. 233. 



Spongilla lacustrioides MacKay, 1885, p. 240. — Potts, 1887, p. 187. 



Spongilla lacustris var. abortiva Potts, 1887, p. 191. 



Spongilla lacustris var. montana Potts, 1887, p. 192. 



Spongilla lacustris var. lehighensis Potts, 1887, p. 193. 



Spongilla lacustris var. multiforis Potts, 1887, p. 192. 



Spongilla lacustris var. paupercula Kellicott, 1891, p. 101. — Arndt, 1926, p. 342; 



1928a, p. 64.— Gee, 1931e, p. 45. 

 Euspongilla lacustris var. lieberkuhni Levander, 1901, p. 56. — Gee, 1931e, p. 41. 

 Spongilla microgemmata Swartschewsky, 1901, p. 346. — Annandale, 1918a, p. 



211.— Gee, 1931e, p. 43. 

 Spongilla lacustris var. ineptorum Annandale, 1919c, p. 86. 

 Spongilla Crustacea Kozhoff, 1925, p. 52; 1930, p. 158. 

 Spongilla fenestrata Kozhoff, 1925, p. 50; 1930, p. 158. 



Spongilla lacustroides Kozhoff, 1925, p. 45; 1930, p. 158. — Gee, 1931e, p. 41. 

 Spongilla lacustris var. rhenana Arndt, 1926, p. 342; 1928a, p. 65. — Penney, 1960, 



p. 23. 

 Spongilla lacustris vox. jordanensis Arndt, 1926, p. 342; 1928a, p. 64. — Schroder, 



1929, p. 87; 1932b, p. 129; 1938a, p. 295.— Pennej^ 1960, p. 23. 

 Spongilla lacustroides corticea Kozhoff, 1930, p. 158. 



Spongilla lacustris var. Crustacea Gee, 193 le, p. 38. — Penney, 1960, p. 22. 

 Spongilla lacustris var. fenestrata Gee, 1931e, p. 38. — Penney, 1960, p. 22. 

 Spongilla lacustris var. lacustroides Gee, 1931e, p. 40. — Penney, 1960, p. 23. 



Material. — Extremely numerous specimens and slide material; 

 EUROPE: Sweden, Finland, Netherlands, Belgium, France, Switzer- 

 land, Germany, Austria, Hungary, Czechoslovakia, Poland, Yugo- 

 slavia, Italy, U.S.S.R.; NORTH AMERICA: U.S.A., Canada; 

 ASIA: U.S.S.R., China, Japan. 



Description. — Mature sponge almost invariably producing long 

 cylindrical branches arising from an irregular base; in lotic environ- 

 ment branches often reduced or absent; surface typically hispid, 

 rarely even; oscula rather inconspicuous and small, dermal membrane 

 well developed. Skeleton consisting of polyspicular longitudinal fibers, 

 coated together in thick sheaths of spongin; and of a varying number 

 of secondary transverse fibers. Consistency of live sponge soft but 

 fairly firm, skeleton of dry sponge extremely brittle. 



Megascleres slightly curved or straight amphioxea, usually fusiform, 

 invariably entirely smooth; length range 200-350 ^, width range 

 6-18 (X. 



Microscleres in varying abundance in dermal membrane and 

 symplasm, slightly curved amphioxea, entirely covered with small 

 spines or granules of almost equal size and distribution; length range 

 70-130 fi, width range 2-8 fi. 



Gemmoscleres, whenever present, rather stout and slightly to 

 strongly curved amphioxea or amphistrongyla, usually covered with 

 strong, curved spines, only exceptionally smooth; length range 80- 

 130 n, width range 3-10 fi. 



