318 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



ure of G. stellata (1906, p. 37, fig. 1), owing to the small subdermal 

 spaces which surround and open into the central space. Adjacent 

 chone vestibules are interconnected by these small spaces, which, 

 lie in the trabecular regions. 



The chief radial megasclere is the orthotriaene ; rhabdome 

 2.5-3.5 mm. long, greatest thickness 70 tx; clads 200-260 [x long, basal 

 thickness 50 [x. 



Oxeas measuring 2 mm. by 35 jx, together with smaller ones, are 

 common in the radial bundles and very numerous in the interior 

 where they cross in all directions. The radial cortical oxeas are 

 closely set, project a short distance, and measure 200-300 by 6 |x. 

 Among the large projecting megascleres are some fusiform oxeas 

 2.8 mm. by 100 [x ; these are probably foreign. 



Anatriaenes are fairly abundant among the radial spicules, cla- 

 dome rather deep in the mature spicule, clads 50-100 [x long and 

 strong, rhabdome 5-7 mm. long and 15-30 jx thick. These spicules 

 occur also among the megascleres which project beyond the surface. 



Protriaenes with clads 70-100 p. long, occasionally up to 150 jx 

 long with rhabdome several millimeters long and 18-30 [x thick, occur 

 among the projecting megascleres. Promesotriaenes, in general simi- 

 lar to the protriaenes, also occur here; the mesoclad of same length 

 as the other clads or somewhat longer, reaching 210 [x in length. 



Sterrastral crust 900-1000 \i thick. Innermost layer of cortex 

 fibrous. Sterrasters are flattened spheroids almost circular in full 

 face view, 80-85 [x in horizontal diameter, 70 jx thick. 



Minute strongylasters, 4-6 jx in diameter, form a dermal crust and 

 are common in ectosome and interior. Centrum about one third the 

 total diameter, with 7-8 ra}s that taper toward the end. 



Cortical spherasters, 24—32 jx in diameter, especially abundant in 

 the extra-sterrastral layer of the cortex, also elsewhere in the ecto- 

 some and in interior. Rays very numerous, exceedingly short, larger 

 at the base, truncated and rounded terminally. 



Polyactinal oxyspherasters, 16-20 |x in diameter, occur in the deeper 

 ectosome and in interior. Centrum about one third the total diam- 

 eter; rays numerous, tapering. 



The oxyasters of the choanosome have 6-7 long tapering, minutely 

 spinulate rays, blunt terminally ; centrum absent, rays 20-32 [x long, 

 total diameter of spicule 44-60 ;jl. 



Holotype.—Cat. No. 21266, U.S.X.M. 



Geodia japonica has been hitherto described only from Japan. 

 The type reaches a large size, 0.5 meter in diameter (Thiele), is 

 usually vasiform or saucer-sharped but may be massive; outer sur- 

 face chacteristically lobose. Where the canals open directly on the 

 surface (Lendenfeld, 1910, p. 72), the dermal membrane has doubt- 

 less been rubbed off. 



