64 THE SPONGES OF THE WEST-CENTRAL PACIFIC 



easily torn. This may mean that it was of another species, only super- 

 ficially similar. On the other hand, it more likely represents an ecological 

 modification. As noted above this specimen was growing on the underside 

 of a mass of dead coral and may have grown very slowly. 



The surface is level, punctiform, and quite typical of the genus Haliclona. 

 The pores are large, up to as much as 600 fx in diameter, and often about 1.3 

 mm apart. The oscules range from 1 to 8 mm in diameter but are commonly 

 between 3 and 7 mm in diameter and 1 to 2 cm apart. Typically, there is a 

 low rim around the oscule, but this is not always present, probably for eco- 

 logical reasons such as strength of current at the point of growth. 



The ectosome is nonexistent, and the interior is principally an isodictyal 

 reticulation with protoplasmic structures more common than in other mem- 

 bers of the genus Haliclona. The flagellate chambers are spherical, about 

 25 jit in diameter. 



The skeleton is principally isodictyal and is built of oxeas which fall 

 loosely into two ill-defined categories. Those of the larger size are about 

 4 n by 130 /x to 5 /a by 140 ll in dimensions. Some are as large as 6 /x by 

 130 ix. The smaller sizes of oxeas may range from 0.5 ju. by 45 /x to 3 /x by 

 124 fx. A distinct possibility exists that these are juvenile, but in all parts of 

 the world there is a general tendency toward this loose grouping into two 

 spicule sizes within the species viridis. In addition to the isodictyal reticula- 

 tion, there are more or less vague tracts which make a large-meshed reticula- 

 tion if considered by themselves. These tracts are often about 25 lk in diam- 

 eter and contain six spicules per cross section. 



This species was first described as Amphimedon viridis by Duchassaing 

 and Michelotti, 1864, page 81, from the West Indian region. It was trans- 

 ferred to Haliclona by de Laubenfels, 1936, page 42. It is extremely 

 abundant in the West Indian region. In 1911, page 316, Row described a 

 sponge from the Red Sea as Reniera tabernacula. Burton in 1937, page 18, 

 transferred this appropriately to the species viridis, which seems therefore to 

 be a circumequatorial species. In this 1937 reference, Burton regards viridis 

 as type of a genus H emihaliclona, but the relationship to the type of Haliclona, 

 that is to say H. oculata, is so close that there does not seem to be adequate 

 reason for establishing a second genus. On the other hand, the genus Hali- 

 clona has become so large as to be unwieldy, so that for purposes of con- 

 venience, if nothing else, a further subdivision of it may be wise. 



SUBGENUS RENICLONA, new 



The genus Haliclona has now about two hundred species names. A 

 few are not well known, and others will doubtless prove to be synonyms ; 

 but the residue remains uncomfortably close to two hundred. 



