100 THE SPONGES OF THE WEST-CENTRAL PACIFIC 



The sponge is so thin that no distinction can be made between ectosome 

 and endosome. There is but the single layer of fibro-reticulation, whose 

 meshes are filled in with thin protoplasm; and the pores (if they may so be 

 called) penetrate quite through this layer. 



The skeleton consists of fibers about 50 p. in diameter, outlining meshes 

 which vary from 100 p. to 400 /x in diameter and are frequently triangular or 

 rounded. There are also fairly numerous spicules in these fibers, which are 

 oxeas 3 jx by 98 p. in dimensions. 



Other than the following species, the species pinella is unique within the 

 genus Pellina because of the very small size of its spicules. Row, 1911, 

 page 316, described a sponge as Reniera tabernacula from the Red Sea re- 

 gion; and Burton, 1926, page 74, transferred it to Pellina. This sponge 

 has similar small spicules, but it is far from certain that it really belongs in 

 the genus Pellina. Row had only a small fragment for description, and it 

 is suggested here that it is essentially unrecognizable. 



Pellina carbonilla, new 



Text Figure No. 62 



This species is here represented by the following : 

 U.S.N.M. No. 22972, My No. M. 348, here described as type, collected July 

 5, 1949, by hand while wading in the Pearl Pool near the western portion 

 of the lagoon at Ebon Atoll. The depth was low tide mark, and the 

 substrate was dead coral. This species was quite common in this region. 



This species is basically incrusting, but numerous processes rise from 

 the basal mass to a height of at least 4 cm. Lateral growth is indefinite, but 

 most specimens were about 4 cm in diameter. The processes, being obviously 

 oscular, are hollow with very thin walls. 



The ectosome and endosome color in life was black, and the consistency 

 weakly spongy. 



The surface is finely tuberculate ; but pore diameters could not be made 

 out, as they are closed in the specimens soon after collection. The oscules 

 are about 3 or 4 mm in diameter and are represented by the apices of the 

 processes. A few are as much as 8 mm in diameter. The oscules are very 

 numerous over the entire sponge. 



The ectosome consists of a tangental layer of spicules arranged in iso- 



Text Figure No. 62. Two of the spicules (oxea) of Pellina carbonilla, X 781. 



