52 



THE SPONGES OF THE WEST-CENTRAL PACIFIC 



ORDER HAPLOSCLERINA Topsent (or HAPLOSCLERIDA*) 



FAMILY HALICLONIDAE de Laubenfels 



GENUS ACERVOCHALINA Ridley 



Acervochalina velinea, new 



Text Figure No. 30 



This species is here represented by the following : 

 U.S.N.M. No. 22854, My No. M. 148, here designated as type, collected on 

 July 7, 1949, by diver at the southeast side of the lagoon at Ebon Atoll. 

 The depth was about 2 meters, and the substrate was a gorgonian. This 

 is remarkable because gorgonians are quite rare in the shallow waters in 

 this vicinity. A few more specimens, probably of the same species, 

 were observed; but the species could not be described as common. 



This species is incrusting, reaching a vertical measurement of about 

 3 mm and spreading indefinitely over the ramose gorgonian. 



The color in life was a light blue on the exterior and very pale drab on 

 the interior. The consistency was softly spongy and notably slimy. 



The surface is conulose, but not the sort of fibrous conules which charac- 

 terize the order Keratosa. Those of the present species are about 0.7 mm 

 high and 1.4 mm apart. The pores are microscopic and apparently close upon 

 death. The oscules are small, about 1.2 mm in diameter, and widely scattered. 



Characteristic of the family Haliclonidae, the ectosome is nonexistent. 

 Nearly the same structures that characterize the endosome continue to, and 

 stop at, the surface. The endosome is fibro-reticulate with the soft parts 

 rather widely scattered instead of being densely aggregated. 



Text Figure No. 30. A: Portion 

 of the fibrous skeleton of Acer- 

 vochalina velinea, X 182. 



B: One of the spicules (oxea) of 

 Acervochalina velinea, X 781. 



* See footnote on page 4. 



