72 U.S. NATIONAL MUSEUM BULLETIN 272 



dermal membrane and symplasm; and the gemmular porus tube is 

 of considerable length. 



Radiospon gilla cantonensis (Gee, 1929) 



Plate 5, figures 19-22 



Ephydatia crateriformis var. cantonensis Gee, 1929c, p. 1; 1930b, p. 170; 1930e, 



p. 27; 1931e, p. 35; 1932d, p. 53; 1932c, p. 28. 

 Meyenia crateriformis var. cantonensis Penney, 1960, p. 48. 



Material.— SHdes of type (USNM, N. Gist Gee). 



Description. — Sponge, according to Gee (1929c), forming a thin 

 layer over the sm-face of small clods of clay; surface of live sponge 

 apparently not yet recorded. Skeleton consisting of slender vertical 

 spicule fibers, made up from 3-5 spicules, and of irregular transverse 

 bundles of scleres, joined together by a small amount of spongin. 

 Consistency of live sponge apparently fragile, texture loose. 



Megascleres fusiform and sharply pointed, almost straight amphi- 

 oxea, armed with a great number of conspicuous acute spines, except 

 at their very tips, length range 180-230 n, width range 8-11 /x. 



Microscleres absent. 



Gemmoscleres invariably straight amphistrongyla, theu' shaft 

 abundantly armed with long acute spines arising from a wide base, 

 and terminally with a singular arrangement of a number of slightly 

 recurved spines, so that almost perfect rotules of umbonate shape are 

 produced; length range 65-72 /x, width of shaft about 5 ju, diameter 

 of rotules 8-9 ijl. 



Gemmules numerous in mature sponge, spherical, scattered through- 

 out the skeletal meshes, and easily dislodged; diameter ranging 365- 

 410 m; pneumatic layer well developed and thick, consisting of minute 

 spherical air spaces; gemmoscleres embedded in this layer strictly 

 radially, arranged in a single layer, not protruding through outer 

 gemmular membrane; foramen distinctly tubular, porus tube short 

 and inconspicuously curved, surrounded by a conical depression 

 caused by slanting gemmoscleres in its vicinity. 



Distribution. — Known only from mainland China. 



Color in life. — Not yet reliably recorded. 



Discussion. — The gemmoscleres of this species, with their straight 

 shafts and almost perfect terminal rotules of umbonate spines, 

 resemble in many regards birotulates of other genera, in particular 

 those of Umborotula. However, the rotules of R. cantonensis are 

 extremely small and lack a central disk and can thus be rather com- 

 pared with the termmal arrangement of radiating spines on the 

 gemmoscleres often present in a number of Radiospongilla species. 

 Although Gee (1929c) considered the species discussed a mere race of 



