132 U.S. NATIONAL MUSEUM BULLETIN 2 72 



Material. — Specimens and slides from Granite City, 111. (USNM 

 no. 8438), Fish Hatchery at Marion, Ala., Virdigris R., Okla., Ohio R., 

 Loyola University, La., Illinois; also from New Orleans (Gee no. 

 53037), Everglades, Fla. (USNM no. 6183), Rio Grande, Tex., and 

 Arkansas (USNM no. 8459) ; syntype of H. plumosa Weltner (slide of 

 type in ZMB, now at USNM). 



Description. — Sponge usually forming bulbous masses; surface of 

 live specimens not yet reUably recorded. Skeleton consisting of well 

 defined radial and irregularly arranged slimmer transverse spicule 

 fibers. Consistency moderately soft but very brittle. 



Megascleres sUghtly curved, slender, and distinctly fusiform am- 

 phioxea, ranging from entirely smooth to distinctly microspined; 

 length range 290-400 /x, width range 14-23 n. 



Microscleres moderately abundant in the symplasm and the 

 vicinity of gemmules; they are stellate spicules consisting of 6-8 

 rays projecting from a distinct central nodule; the rays usually 

 microspined, terminating in a small number of minute reciu-ved 

 distal spines arranged in the shape of a small rotule; occasionally 

 transitional amphioxous microscleres, distinctly granulated, and 

 bearing in their central portion a number of perpendicular long rays; 

 length range of microscleres extremely variable. 



Gemmoscleres of two conspicuously distinct classes : (1) Birotulates 

 of shghtly but distinctly unequal length, with a strongly spined 

 cylindrical shaft, and terminally with umbonate rotules of equal 

 diameter whose margins bear an irregular arrangement of triangular 

 teeth; and (2) extremely long birotulates of greatly varying length, 

 their shafts often bent and smooth, occasionally bearing a few spines, 

 their rotules represented by a small number of strongly recurved 

 hooks; shaft cylindrical, as a rule distinctly fusiform, resembling the 

 shape of megascleres; length range of (1) 45-82 ju, thickness of shaft 

 8-19 n, diameter of rotules 22-26 fi; length range of (2) 120-230 /x, 

 thickness of shaft in central portion 16-20 n. 



Gemmules spherical, ranging in diameter 540-610 /x; pneumatic 

 coat well developed, consisting of minute spherical air spaces; smaller 

 class of gemmules within this coat, larger class invariably projecting 

 through its outer surface, often for a great distance; foramen pro- 

 duced into a short and straight tube, projectmg through pneumatic 

 coat but not surpassing its outer surface. 



Distribution. — Ranging from the Canadian border south to 

 Mexico. 



Color in life. — Apparently not yet recorded. 

 Discussion. — Dosilia radiospiculata agrees with the three preceding 

 species in all structural and spicular details, but in addition it possesses 

 an extremely large and distinctly heterogeneous class of longer 



