AET. 4 SPONGES OF CALIFORNIA dk LAUBENFELS 117 



usually short and thick, packed close together in tracta. The most obvious 

 feature of this genus is its hard, often stony texture. 



It would seem that two distinct generic types are included in the 

 sponges assigned to the above diagnosis. One group typically has 

 large thick strongyles, plus large thick oxeas plus very small spicules 

 apparently representing a distinct category, because they are found 

 of considerable diameter although short. The spicules that seem 

 clearly to be immature are nearly as long as, though much thinner 

 than, the type they are approaching by their growth. The ectosome 

 seems unknown for the genotype, but most of the species having the 

 above characteristics, as for example Petrosia Ugnosa Wilson (1925, 

 p. 403), have special dermal tangential skeletons. A second group 

 lacks this ectosmal specialization and therefore may be taken as wor- 

 thy of generic separation ; a further parallelism seems to be that this 

 group has only oxeote spicules. I would suggest that the group 

 exemplified by Petrosia Ugnosa and probably by the genotype, 

 P. dura^ is most closely related to Gellius and Strong ylophora (and 

 possibly even to naUcliondria ?), while the second group is most 

 closely related to Haliclona,. The second group comprises several 

 sponges described by Dendy, for example Petrosia densissima (1905, 

 p. 145) and coraUoldes (1924, p. 324), and perhaps several other 

 species, such as P. variahiUs Ridley (1884, p. 415), P. similis Ridley 

 and Dendy (1886, p. 327), and P. fsfulata Kirkpatrick (1907, p. 

 290). Most of the earlier authors and some of the later ones fail 

 to give adequate data concerning surface structure. The new generic 

 name Xestospongia is proposed for this latter group. 



Genus HALICLONA Grant 



nALICLONA ECBASIS de Laubenfels 



EaUclona ecbosis de Laxjbenfels, 1930, p 28. 



Holotype.—V.S.'NM. No. 21449; paratype, B.M. No. 29.8.22.48. 



Type locality. — From the floating dock of the Yacht Club in San 

 Diego Bay, Calif., collected by Prof. C. M. Child. 



Additional niatei^ial examined. — I have found the same species 

 growing abundantly on the floating dock of the Yacht Club at 

 Wilmington (near San Pedro). On March 4, 1926, I found small 

 bits of an encrusting sponge, intertidal, at Laguna Beach, which 

 may be of the same species. 



Descnption. — Shape, ramose or digitate, often with an axial hollow 

 about one-third the diameter of the branch. Size, up to 10 cm high, 

 about 1 cm in diameter. Consistency, spongy. Color in life : Prof. 

 C. M. Child, writing of his specimen, collected during the summer, 

 says: "The color in life is purple, apparently becoming brown later 



