THE SPONGES OF THE WEST-CENTRAL PACIFIC 197 



The surface is beset with projecting fibers 2 to 3 mm high and about 

 3 mm apart, between which conspicuous openings show. These are probably 

 the pores and are about one for each square mm. They are several hundred fi 

 in diameter. The oscules are 3 mm in diameter and 1 to 3 cm apart. 



The ectosome consists of a dermis 15 /x thick, consisting first of proto- 

 plasm, but containing many tangentally arranged spicules. It is set off from 

 the endosome by extensive and conspicuous subdermal cavities. The endosome 

 contains notable fibers in vague reticulation. 



As noted above the skeleton consists of fibers which are about 500 /a in 

 diameter, containing approximately 150 spicules per cross section. These 

 spicules are exclusively oxeas, 2 tt by 280 /x to 10 [x by 300 /x in dimensions. 



Burton, 1934, page 12, described Hoplochalina glacialis from the Ant- 

 arctic. This has spicules very much smaller than those of any others in the 

 genus. At present, other than this, there exist in Hoplochalina four additional 

 species names, all erected by Lendenfeld for specimens from Australia. The 

 descriptions of each one of these sounds very much like the descriptions of all 

 the other three, and it is here suggested that they represent but a single 

 species, which may be known as Hoplochalina dendrilla Lendenfeld, 1887, 

 page 823. The species names which are dropped in synonymy to dendrilla are 

 incrnstans, renieroidcs, and tenella, all by Lendenfeld, 1887, page 823. The 

 species agoga is close to dendrilla, but the latter has spicules which are 

 13 [x by 500 ji and, therefore, are much larger than those of agoga. Dendrilla 

 has also a pronounced tendency to ramose form and has a less ornate surface. 



The name agoga is an arbitrary conbination of letters, without descriptive 

 significance. 



ORDER HADROMERINA, Topsent (or HADROMERIDA*) 



FAMILY CHOANITIDAE de Laubenfels 



GENUS SPIRASTRELLA Schmidt 



Spirastrella potamophcra, new 



Text Figure No. 134 



This species is here represented by the following : 

 U.S.N.M. No. 22965, My No. M. 339, here designated as type, collected 



July 2, 1949, by diver at Majuro Atoll in the southeast corner of the 



lagoon near Te-elop Islet. The depth was 2 meters, and the substrate 



was dead coral. 

 U.S.N.M. No. 22934, My No. M. 304, collected June 11, 1949, by hand 



while wading at Ailing-lap-lap Atoll in the south portion of the lagoon 



near Bikajela Islet. The depth was near low tide mark, and the substrate 



was dead coral. 



See footnote on page 4. 



