ART. 4 SPONGES OF CALIFORNIA de LAUBENFELS 113 



Desci^lption. — Shape, concavo-convex lamellate. Size, 1 cm thick, 

 about 12 cm in diameter. Consistency, fragile. Color in alcohol, 

 very pale drab. Oscules (on the concave side only), diameter O.T 

 to 1.2 mm; distance apart, about 6 mm. There is a very thin (lOju,?) 

 transparent membrane over the entire oscular surface, except for 

 the openings of the oscules themselves, and it even closes them par- 

 tially, in a sphinctrate manner. Pores, apparently only on the 

 convex side. The above-mentioned dermis also covers the porous 

 surface. The meshes of the skeleton are 0.7 to 1.1 mm in diameter, 

 but the round apertures in the dermis, which may be considered the 

 real pores, are but 100/a to 200/a. Surface, superficially smooth. 



Ectosomal specialization, an optically evident reticulation of large 

 spicules; the polygonal meshes are 0.5 to 0.8 mm in diameter. This 

 dermal skeleton is about 0.2 mm thick. Endosomal structure, in 

 places a typical renierid isodictyal reticulation with spongin nodes, 

 elsewhere confused and vague. Most of the microscleres are endo- 



FiGDRE 67. — OelUus textapatina de Laubenfels, X300 



somal. Histological details : There are spherical flagellate chambers 

 of very great variation in size, namely, from about SO^u, to 60^ in 

 diameter. There are also fairly numerous embryos, about 350/i, in 

 diameter, grouped principally about the canals in the deeper portions 

 of the endosome. A few of them have fairlv numerous full-sized 

 sigmas and minute straight rhabds in their peripheral region. 



Principal spicules, oxeas (fig. 67, ^) ; size, 20^ by 340/x to 22/x by 

 460ja. Microscleres, sigmas (fig. 67, B) ; length, 50/^ to 80/i,. 



Re^inarhs. — The almost complete lack of microscleres in the ecto- 

 some is remarkable. Both megascleres and microscleres are large as 

 compared to most species in the genus. 



HALICHOCLONA, new genus 



The genus may be briefly characterized by comparison. It has 

 the endosome of Haliclona (isodictyal reticulation of oxeas) plus the 

 ectosome of Halichondria (detachable, with a definite dermal skele- 

 ton of tangential spicules). It may also be described as Gellius with- 

 out the sigmas. Genotype, Halichoclona gellindra^ new species. 

 107704—32 8 



