ART. 4 



SPONGES OF CALIFORNIA de LAUBENFELS 



115 



altered by its growth within the surface of the macerated tetraxon 

 sponge. The specimen from central California was alive and in 

 excellent condition, however. All our local Gellius species have 

 spicules very much larger than either of the specimens above re- 

 ferred to the new^ genus Halichoclona. 



We may eventually merge all genera that are alike except for 

 differences in microscleres, though there are practical reasons for 

 depreciating such amalgamation. For the present there seems good 

 reason for retaining this as distinct from Gellius. 



XESTOSPONGIA, new genus 



This genus is characterized by having only oxeas as spicules and 

 these so abundant that any reticulate arrangement is obscured; 

 there is no special dermal skeleton. Genotype, Xestospongia 

 diprosofia. 



XESTOSPONGIA DIPROSOPIA (de Laubenfels) 



Huliclona diprosop'm de Laubenfels, 1930, p. 28. 



Holotijpe.—V.S.^.'M. No. 21509 ; B.M. No. 29.8.22.59. 



Type locality. — The one specimen was collected in Monterey Bay, 

 Calif., depth about 500 meters, by E. F. Ricketts. 



Description.- — Shape, lamellate. Size, 1 to 4 cm thick, 6 by 12 cm 

 in area. Consistency, friable. Color dry, very pale drab. Oscules, 

 on one side only; diameter, 3 mm; distance apart, 15 mm; over very 

 shallow cloacas 

 that branch almost 

 at once into about 

 a dozen diverti- 

 cules. Pores, at 

 least 100/x in di- 

 ameter; principal- 

 ly on the nonos- 

 cular face. Sur- 

 face, superficially smooth, with low rounded protuberances 5 to 15 

 mm liigh on the oscular surface. 



Ectosomal specialization, lacking, although there is a false appear- 

 ance as of a special ectosomal reticulation, because of the fact that 

 the endosomal reticulation is finer above and coarser below. En- 

 dosomal structure, reticulate, with polygonal meshes about 0.5 to 

 0.7 mm in diameter, bounded by fascicular bundles of spicules. The 

 spicule size is notably uniform. 



Principal spicules, oxeas (fig. G9) ; size, about 30//, by 400/t. 



Remarks. — This specimen was collected from the same general 

 locality as Gellius textapatina and Poecillastia rickettsi and is note- 



FiGDRE 69. — Xestospongia diproaopia (de Laubenfels), X300 



