38 U-S. NATIONAL MUSEUM BULLETIN 272 



brane or membranes. In both S. sinensis and S. stanleyi the pneumatic 

 layer always consists of clearly discernible polygonal air spaces, and 

 the gemmoscleres are amphioxea, in contrast to the Stratospongillo^ 

 spp., as restricted in this paper, whose gemmoscleres are typically 

 sausage-shaped amphistrongyla. Even if Rezvoj's (1930) view that 

 S. stanleyi and S. sinensis represent intermediate forms between 

 Eunapius and Stratospongilla is taken into consideration, the general 

 characteristics of both these species seem to fit much better into the 

 definition of the former genus. 



The only criterion differentiating S. stanleyi from S. sinensis, as 

 described by Annandale, is the shape of the gemmoscleres in both 

 species, being rather irregularly spiny in the former and almost 

 entirely smooth in the latter. The structure, consistency, and skeletal 

 components of both species are fully identical, and so are form, 

 pneumatic coat, and armature of the gemmules. It is obvious that the 

 sUghtly different gemmoscleres in both species are the result of 

 ecomorphic adaptations, and that the retention of S. stanleyi as a 

 separate species is unwarranted. Future detailed workers will have 

 to decide whether it should be differentiated on a subspecific level. 



Eunapius potamolepis (Annandale, 1918) 



Plate 2, figures 14, 15 



Spongilla {Eunapius) potamolepis Annandale, 1918a, p. 208. 

 Spongilla potamolepis Gee, 1932g, p. 303. 



Material.— Slides of type (IM, Keg. no. ZEV 7164/7). 



Description. — Sponge, according to Annandale (1918), forming 

 thin crusts on sticks and bamboos; surface smooth and without 

 noticeable projections; oscula small and scattered, each approached 

 by a ramifjring horizontal subdermal channel. Skeleton consisting of a 

 close network of single spicules and bundles that are arranged in a 

 polygonal manner. Consistency of live sponge extremely hard and not 

 at all brittle. 



Megascleres, in inner symplasm, rather stout, cylindrical, and entirely 

 smooth amphistrongyla, sometimes inflated at their tips; those in 

 peripheral areas of younger sponges often smooth amphioxea; length 

 range 240-330 ^t, width range 7-17 ^u. 



Microscleres absent. 



Gemmoscleres comparatively short and stout, cylindrical, and 

 abruptly pointed amphioxea, entirely covered with minute spines; 

 length range 80-105 p,, width range 4-9 p. 



Gemmules moderately abundant to very rare in mature sponge, 

 subspherical, diameter of inner gemmular membrane about 300 p) 

 confined to base of sponge, usually forming distinct pavement layer, 

 and tightly adhering to support; pneumatic layer well developed and 



