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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 81 



100/A in diameter when open, and about 200ju, from center to center 

 over almost the entire surface. The oscules are chones, diameter 

 about 500yu, to 600^, with the sieve openings 100/a to ISO^a. Surface 

 superficially very hispid. There is a dense spicule fur 3 mm high, 

 composed of erect spicules. As is often true of tetraxon sponges, 

 this spicule plush renders the sponge more dangerous to touch than a 

 cactus plant; numerous spicules penetrate the skin and are removed 

 only with much pain and difficulty. 



Figure 11. — Stelletta clarella de Laubenfels : A to O, X^O; others, X 1,333. A, 

 either end of the ectosomal oxea, or the esactinal termination of the ana- 

 triaene ; B, either end of the endosomal oxea, or the esactinal termination of 

 the plagio spicule ; C—G, variations of the principal radiate spicule. Any of 

 this spicule sort may be diaene instead of triaene in this species. The range 

 from orthotriaenes through plagiotriaenes to dichotriaenes is a matter of age ; 

 H~J, anatriaenes ; K-N, euasters ; 0, P, siliceous structures 



Ectosomal specialization, corticate, cartilaginous, about 1 to 2 mm 

 thick. Endosomal structure, the smaller masses are strongly radiate 

 in structure and even in the larger encrustations the structures with- 

 in about 1 cm of the surface are strongly marked by fascicular 

 columns of spicules perpendicular to the surface. 



Principal spicules, oxeas (fig. 11, B) ; size about 50/a by 3,500/a. 

 Ectosomal spicules, oxeas (fig. 11, A); size about 15/* by 1,400/x. 

 Interstitial spicules, anatriaenes (fig. 11, H, /, /) ; size of rhabds 9/* 

 by l.lOO/x to 15/x by 2,000/a, chords 45/i, to 90/t. Chief radiate spicules 



