REVISION OF FRESHWATER SPOXGES OF SPONGILLIDAE 109 



Heteromeyenia baileyi var. arndti Schroder, 1927a, p. 75; 1927 b, p. 107. — Zimmer, 



1936, p. 126. 

 Heteromeyenia baileyi var. bohemica Schroder, 1927b, p. 107. — Arndt, 1928a, p. 78, 

 Heteromeyenia baileyi var. palatina Schroder, 1927b, p. 107. 

 Heteromeyenia baileyi var. petri Schroder, 1927b, p. 107. — Arndt, 1928a, p. 74. — 



Gee, 1928, p. 225; 1929b, p. 13; 1930e, p. 27; 1931e, p. 46.— Sasaki, 1934, 



p. 241.— Zimmer, 1936, p. 126. 

 Heteromeyenia baileyi var. stepanowi Schroder, 1927b, p. 107; 193Sb, p. 127. — 



Grimailowskaja, 1928, p. 215. 

 Meyenia hungarica Traxler, 1888, p. 2. 



Material. — Numerous specimens and slides; EUROPE: Czecho- 

 slovakia, Germany, Poland, U.S.S.R.; ASIA: China, Japan; AUS- 

 TRALIA: New South Wales. 



Description. — Sponge forming delicate and shallow cushions on 

 aquatic plants or dead branches; surface usually even but always 

 distinctly hispid due to projection of spicule fibers through dermal 

 membrane. Skeleton forming a rather regidar network of long spicule 

 fibers, joined together by a considerable amount of spongin. Con- 

 sistency of live sponge moderately firm, 



Megascleres fusiform and slender, sharply pointed amphioxea, 

 sUghtly curved to almost straight, sparsely covered -wdth inconspicuous 

 spines except at their extremities; length range 180-310 /z, width 

 range 8-11 n. 



Microscleres delicate, fusiform, and sharply pointed amphioxea, 

 slightly curved, spined throughout their length; spines increasing in 

 length towards the central portion of the scleres, where they are 

 perpendicular and often end in knoblike expansions; length range 

 78-86 n, width range 2-3 ju without spines. 



Gemmoscleres birotulates of two distinct length groups, usually 

 possessing identical rotules, rarely displaying marked differences in 

 the shape of the rotules in the two groups; shafts of both covered with 

 rather long and conical spines, perpendicular to their axes; rotules 

 of equal diameter, shghtly but distinctly umbonate, bearing at their 

 lateral margins a greater number of regular, comparatively smaU, 

 and strongly recurved teeth; birotulates of both classes occasionally 

 malformed, resulting in a projection of the axis through the rotules, 

 or in an iiTegidar incision of their margin; length range of longer 

 class 75-88 m, of shorter 58-65 n; diameter of rotules in both about 

 18 fji. 



Gemmules moderately abundant in mature sponge, ranging in 

 diameter 430-520 n, spherical; pneumatic layer well developed and 

 granular, consisting of minute spherical air spaces; width of this 

 layer ranging 28-42 /x, so that both classes of gemmoscleres project 

 beyond the outer gemmular membrane; foramen distinctly tubular, 

 tube moderately long and slender, terminally bearing a crownhke rim. 



