REVISION OF FRESHWATER SPONGES OF SPONGILLIDAE 155 



two distinct length groups, the smaller series then forming spicular 

 cages around the gemmules; occasionally the smaller set only covered 

 with irregular granulations. 



Microscleres of varying abundance, always slender, fusiform and 

 spiny amphioxea; present in symplasm and often participating in the 

 protection of the gemmular pneumatic layer. 



Gemmoscleres parmuliform, consisting of a large rotule with an 

 internal conical depression and of more or less circular outline, and a 

 short tapering stem without distal reinforcements. 



Gemmules very large and spherical, scattered through skeletal 

 meshwork, held in position by surrounding capsules of smaller mega- 

 scleres, or without such cages; pneumatic layer either very thin, 

 containing one to more immediately adjoining parmuliform gem- 

 moscleres, or thick and distinctly corrugated, holding an outer and 

 an inner gemmosclere layer separated by a wide granular space; 

 microscleres used in varying abundance for an additional protection 

 of the gemmules, only rarely absent; foramen produced into a wide 

 and short tubule, bearing a distinct peripheral collar. 



Sponges forming nodulose to spherical growths on submerged 

 twigs; surface coarsely reticidate and strongly hispid. Coloration 

 usually a dark brown. Consistency very rigid to hard, but often 

 brittle. 



Apparently restricted to tropical South America, but local dispersal 

 still insufficiently known. 



Discussion. — Carter (1881a), by rejecting the entire system of 

 Gray (1867), introduced the generic name Parmula for two of Gray's 

 three species of Drulia, Spongilla batesii Bowerbank and S. hrownii 

 Bowerbank. Although it defied the obvious priority of the well 

 defined genus Drulia, this arrangement remained unchallenged for 

 more than 50 years. De Laubenfels (1936), in giving a somewhat loose 

 comment on all spongillid genera, correctly referred to S. hrownii 

 as the type species of Drulia, but he erroneously claimed it to be 

 characterized "by the great difference between the size of the discs 

 on its birotulates." That author, apparently unaware of the similar- 

 ity of gemmoscleres within the genus Drulia, as here redefined, also 

 retained Carter's genus Parmula and established S. batesii Bowerbank 

 as its type species. Thus it happened that Jewell (1952) and Penney 

 (1960) listed both Drulia and Parmula and distributed the various 

 species between these two genera. 



It will be shown in the discussion of S. batesii and S. brovmii that 

 both are certainly distinct species, but the use of their distinguishing 

 criteria for a generic separation is fully unwarranted. In spite of its 

 wide use by spongUlid systematists, Parmula Carter cannot be 

 retained and must now be relegated to a synonym of Drulia Gray, 



