16 



PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 81 



MateHal examined. — Numerous California specimens were studied. 

 The species is very common in the intertidal zone both in southern 

 California and the Monterey region; and E. F. Ricketts reports 

 seeing sponges resembling this at various intermediate points. The 

 University of Southern California dredged it in 27 meters off Long 

 Beach. It often hangs from the underside of bowlders, and as ex- 

 posed at low tide makes beautiful pearllike pendants. 



Description (U.S.N.M. No. 21486; B.M. No. 29.8.22.43).— Shape, 

 vasiform, elongate, stipitate. Size, up to 5 mm in diameter, 25 mm 

 high. Consistency, mediocre. Color in life and when preserved, 

 white. Oscules, apical; diameter up to 3 mm. There is a small 



D 



,-/>'- AW/// ill /Id 



FtGURB 7. — RJiabdodirmeUa tiultingi Urban: Spicules (limits of pro- 

 toplasmic structures indicated by dotted lines) in a cross section 

 perpendicular to the long axis of the sponge, the various sorts 

 except the coronal oxeas in situ, X95. The upper portion of the 

 figure is the external, the lower is the cloacal 



coronal palisade of erect spicules. Pores, up to 200/i in diameter. 

 Surface, superficially smooth. 



Ectosomal specialization, the dermis (20ju, thick) contains distinc- 

 tive microrhabds, placed vertically, in great abundance. Endosomal 

 structure, leuconid of the sort termed sylleibid, that is, with the 

 flagellate chambers in grape-cluster arrangement. Histological de- 

 tails : The flagellate chambers are oval, about TO/x by 126ju, in size. 



First type of spicules, coronal oxeas (not figured) ; size about 25/i 

 by 1,250/i. Second type of spicules, large hypodermal quadriradiates 

 or triradiates (fig. 7. A)', size of rays, about 40/* by 875/x. Third 

 type of spicules, smaller triradiates (fig. 7, B) ; size of rays, about 

 lOfjL by 230/x. Fourth type of spicules, very small quadriradiates or 

 triradiates (fig. 7, (7) ; size of rays, about 4/i, by 20ix to 5/x by lUU/x„ 

 Microscleres, microxeas (fig. 7, Z>) ; size, about 2|U. by 45/x. 



