82 PEOCEEDINGS OF THE NATIONAL MUSEUM vol.81 



Similar species of this genus are reported from nowhere else, the 

 complete absence of microscleres being noteworthy. 



As noted under Myxilla parasitica, I collected another myxillid 

 sponge in California with no microscleres, rather clearly an aberrant 

 form of a common local species. Myxilla versicolor seems the only 

 member of the group definitely attended with such a deficiency, and 

 equally well marked by the peculiar dermal spicule. 



Figure 46. — Myxilla versicolor Topsent calif orniana, iifw variety, 

 X300. C, problematical spicule, probably a very early stage of 

 the megascleres, perhaps an iiiieom'mon microsclei-e (a rhaphide) 



In M. versicolor calif orniana the dermal spicules are also numerous 

 in the endosome, and the typical Myxilla reticulation is lacking. 

 This latter may or may not be true for the Mediterranean form, all 

 of Topsent's specimens having been very thin incrustations. 



Genus lOPHON J. E. Gray 



lOPHON CHELIFER Ridley and Dendy CALIFORNIANA, new variety 



Eolotype.—U.S.'NM. No. 21401 ; B.M. No. 29.9.30.7. 



Type locality. — A handful of fragments of this sponge was 

 dredged by the University of Southern California on December 

 27, 1916, south of San Pedro, Calif., depth 48 meters. 



Description. — Shape, amorphous. Size, the largest fragment is 

 about 2 cm in diameter; the size of the complete sponge (colony) 

 can not be ascertained. Consistency, fragile. Color in alcohol, 

 very dark brown. Oscules, very irregular; diameter, about 1 mm. 

 Pores, minute. Surface, superficially very lumpy and irregular, 



Ectosomal specialization, a dermal membrane; it is fleshy, not 

 easily detachable, and contains few spicules. The tylotes are 

 bunched irregularly at or near the surface. Endosomal structure, 

 " crumb-of-bread," with a dense myxilloid isodictyal reticulation of 

 acanthostyles, cemented together by a small quantity of spongin at 

 the nodes. 



Principal spicules, acanthostyles (fig. 47, J.); size, 12/i by 265jli 

 to 13ju. by 290^. Ectosomal spicules, tylotes with heads microspined 

 (fig. 47, C) ; size, 6^ by 250/* to 8/a by 240|U. Interstitial spicules, 

 smooth styles (fig. 47, B)\ about 3/x in diameter; they are probabl.y 



