88 U-S. NATIONAL MUSEUM BULLETIN 272 



Ephydatia japonica (Hilgendorf, 1882) 



Spongilla fluviatihs var. japonica Hilgendorf, 1882, p. 26. 

 Ephydatia fltiviatiUs var. japonica Weltner, 1895, p. 123. 



Ephtjdatia japonica Annandale, 1909b, p. 112; 1910b, p. 649. — Smith, 1921, p. 17. 

 Ephydatia miilleri va.T. japonica Annandale and Kawamura, 1916, p. 13. — Annan- 

 dale, 1918a, p. 200.— Gee, 1928, p. 222.— Sasaki, 1934, p. 238. 

 Ephydatia miilleri Gee, 1930b, p. 175 (part); 1931b, p. 269 (part). 

 Meyenia miilleri Penney, 1960, p. 51 (part). 



Material. — Slides of syntype (N. Gist Gee) and of a specimen from 

 Japan. 



Description. — Mature sponge forming flat cushions on aquatic 

 plants, occasionally more massive growths; surface often uneven and 

 rough; oscula relatively large and deep in massive forms, incon- 

 spicuous in flat crusts; dermal membrane well developed. Skeleton 

 consisting of an irregular network of multispicular vertical and slender 

 horizontal fibers, joined together by a small amount of spongin. 

 Consistency of live sponge rather soft and fragile. 



Megascleres distinctly fusiform and slender amphioxea, straight to 

 feebly curved, as a rule entirely smooth; length range 220-360 m> 

 width range 12-16 fx. 



Microscleres absent. 



Gemmoscleres birotulates of one class, with a moderately stout 

 and short shaft, as a rule smooth, and terminally with rotules of 

 equal diameter and distinctly flat shape, irregularly and deeply 

 incised into a small number of long rays, usually less than 12; length of 

 shaft 12-15 At, diameter of rotules 16-22 /x, width of shaft 4-6 /x. 



Gemmules abundant in mature sponge, particularly in basal 

 regions, spherical, ranging in diameter 350-520 n; pneumatic coat 

 well developed but shaUow, consisting of minute spherical air spaces; 

 gemmoscleres embedded in this coat in one, only rarely in two layers; 

 outer gemmular membrane feebly developed, distal rotules of gem- 

 moscleres often slightly protruding; foramen slightly elevated, sur- 

 rounded by a narrow collar, never tubular. 



Distribution. — Hitherto considered discontinuous; recorded from 

 the United States, Manchuria, and Japan. 



Color in life. — Ranging from light yellow to gray, occasionally 

 green. 



Discussion. — This species was originally described by Hilgendorf 

 (1882) as a "variety" of E. fluviatilis an error resulting from the failure 

 of Carter (1881a) and a number of subsequent authors to distinguish 

 E. fluviatilis and E. miilleri specifically. Annandale (1909b) at first 

 raised it to full specific rank, but later (1916, 1918a) relegated it to a 

 varietal form of E. miilleri, thus aiding its inclusion within the morpho- 

 metric range of this latter species by Gee (1930b, 1931b) and Penney 

 (1960). 



