THE SPONGES OF THE WEST-CENTRAL PACIFIC 65 



After much field study, it seems reasonably clear that two categories of 

 species do exist within this large group. It may be argued that intermediate 

 categories also exist and that there are undoubtedly specimens difficult to al- 

 locate. While this is true, we notice that, as nature is more thoroughly 

 studied, additional intermediates are repeatedly found — often so many inter- 

 connecting genera occur that even a three-dimensional representation of the 

 result would be a bewildering maze. Because Haliclona specimens do fall 

 into two natural groups and because the two hundred species' size is distress- 

 ingly unwieldy, Renidona is here established to have as its type the species 

 originally described as Isodictya permollis by Bowerbank, 1866, page 278, 

 and transferred to Haliclona by de Laubenfels, 1936, page 40. 



Renidona is here described as persistently incrusting, never ramose. 

 Juvenile specimens of Halidona (which later becomes ramose), may tem- 

 porarily be incrusting; and, therefore, it follows that small, juvenile speci- 

 mens may be very difficult to allocate. Another difference is that Renidona 

 specimens are quantitatively more isodictyal and less fibrous than are speci- 

 mens of Haliclona, which in contrast are less isodictyal and more fibrous. No 

 hard and fast line can be drawn, but the suggestion is made that in case of 

 doubt as between the two any ramose sponge should certainly be regarded 

 as Haliclona even though it is isodictyal. 



Some six species of the new subgenus Renidona are found in the west- 

 ern Pacific area covered in the present paper. In addition to this, a number 

 of species now in Haliclona (or in Reniera) should definitely be regarded as 

 in the new subgenus. They are listed as follows : 



Chalina intersepta Topsent Isodictya mcandrewii Bowerbank 



Chalimda robustior Schmidt Isodictya obscura Bowerbank 



Halichondria condensa Bowerbank Isodictya pallida Bowerbank 



Halichondria palmata (Lieberkiihn Isodictya parasitica Bowerbank 



not Johnston) Isodictya pauper cula Bowerbank 



Haliclona enamela de Laubenfels Isodictya peachii Bowerbank 



Haliclona erina de Laubenfels Isodictya permollis Bowerbank 



Haliclona lunisimilis de Laubenfels Isodictya per pie xa Bowerbank 

 Haliclona stephensi Burton Isodictya pocillum Bowerbank 



Isodictya anomala Bowerbank Isodictya pygmea Bowerbank 



Isodictya clava Bowerbank Isodictya rosea Bowerbank 



Isodictya crassa Bowerbank Isodictya simplex Bowerbank 



Isodictya densa Bowerbank Isodictya simulo Bowerbank 



Isodictya ferula Bowerbank Isodictya tenera Marenzeller 



Isodictya gregorii Bowerbank Pachy chalina grantii Lendenfeld 



Isodictya incerta Bowerbank Pachychalina montqguii Ferrer Her- 



Isodictya indefinita Bowerbank nandez 



Isodictya indistincta Bowerbank Pachychalina oblonga Vanhoffen 



Isodictya luteosa Bowerbank Reniera accomodata Schmidt 



