102 U.S. NATIONAL MUSEUM BULLETIN 272 



Heterorotula multiformis (Weltner, 1910) 



Plate 8, figures 4, 12 



Ephydatia multiformis Weltner, 1910, p. 138. — Gee, 1931e, p. 44; IQBld, p. 53; 



1932c, p. 30. 

 Meyenia multiformis Penney, 1960, p. 53. 



Material. — Slides of syntype (HM) ; two specimens from Western 

 Australia (Racek). 



Description. — Sponge forming encrustations of various dimen- 

 sions, mature specimens slightly bulbous; surface comparatively even 

 and smooth; oscula few in number and very inconspicuous, dermal 

 membrane well developed and adhering to the underlying symplasm. 

 Skeleton consisting of an irregular meshwork of spicule fibers joined 

 together by only small amounts of spongin. Consistency of live sponge 

 soft and very fragile. 



Megascleres comparatively long and moderately stout amphioxea, 

 shghtly cm'ved, and as a rule entirely smooth; length range 330-420 n, 

 width range 13-20 fi. 



Microscleres absent. 



Gemmoscleres birotulates with slender and smooth shaft, only occa- 

 sionally bearing 1 or 2 conical teeth, and terminally with flat rotules of 

 distinctly unequal diameter; faces of rotules shghtly granulated; 

 margin of rotules irregularly incised, bearing a varying number of 

 distinct teeth; length differences of birotulates moderately pronounced: 

 length range of larger series 35-52 ju, of smaller 24-44 ju; width range 

 of lower rotule 14-24 n, of upper 14-18 /x; thickness of shaft 2-4 ju. 



Gemmules abundant in mature sponge, scattered throughout 

 skeletal meshwork; they are large and spherical, ranging in diameter 

 480-680 n; pneumatic layer very thick and irregular but rarely higher 

 than the longest gemmoscleres, consisting of minute air spaces; 

 gemmoscleres embedded in this coat with their larger rotules firmly 

 inserted in the inner gemmular membrane ; outer gemmular membrane 

 distinctly corrugated; foramen simple or bearing a shallow peripheral 

 collar. 



Distribution. — Known only from Western Australia. 



Color in life. — Light brown. 



Discussion. — This species differs from H. multidentata in skeletal 

 details, in the shape of its pecuhar and small gemmoscleres, and in the 

 possession of entirely smooth megascleres. From H. capewelli, with 

 which it shares smooth megascleres, H. multiformis can be distin- 

 guished by its very soft consistency, smooth body surface, conspicu- 

 ously different gemmoscleres and megascleres, and the absence of 

 the latter spicules on its gemmules. The species here discussed is there- 

 fore clearly separable from all its congeners, even though a better 



