THE SPONGES OF THE WEST-CENTRAL PACIFIC 207 



may be absent from these patches, and confined to the grooves between them. 

 These debris-covered patches are about 1 by 2.5 mm in size, and the meander- 

 ing spaces between them are uniformly about 1 mm wide. The endosome is 

 densely micro-cavernous, or bread-like, with large spicules and short tracts 

 showing plainly. 



The skeleton consists of styles of two size ranges, the larger ones 21 /u, 

 by 770 /x and the smaller ones 2 /x by 160 [x. These, as characteristic of the 

 genus Aaptos, are slender for quite a distance near the head, and are largest 

 or swollen about one third of the way from the sharply pointed end. 



Schmidt, 1864, page 33, described Ancorina aaptos from European 

 waters, which was made the type of the genus Aaptos by Gray, 1867, page 

 519. Several other species from European, Mediterranean, and West Indian 

 waters have been referred in synonymy to this species in various of the writ- 

 ings of Topsent. This species, Aaptos aaptos, has spicules far larger than those 

 of Aaptos chromis. In fact, many of them are as large as 42 jx by 1800 /x. 

 In de Laubenfels, 1935, page 8, Aaptos vannamei is described as from 

 Lower California and the eastern Pacific region. This has spicules even more 

 enormous than those of aaptos itself, many being as much as 120 /x by 6000 fx. 

 Thus, the new species from the western Pacific may be characterized by the 

 relatively small size of its spicule type. Its peculiar dermal structures are also 

 worthy of very careful consideration. 



The specific name is derived from the Greek word supposedly indicating 

 yellow or greenish color and is based upon the bright coloration of the interior 

 of this form. 



GENUS RIDLEIA Dendy 

 Ridleia peleia, new 



Text Figure No. 141 



This species is here represented by the following. 

 U.S.N. M. No. 23134, My No. M. 517, here designated as type, collected 

 September 8, 1949, by hand while wading in a bay 5 kilometers north 

 of Ngeremetengel on Babeldaub Island in the Palaus. The depth was 30 

 cm, and the substrate was mud. 



As seen under water, the fairly numerous specimens of this sponge 

 occurring at the point of collection appeared as mere hollow cylinders pro- 

 truding out of the mud, rising a distance of 2 or 3 cm above the surface of 

 the mud, and having a diameter of 2 or 3 cm. Their walls were from 1 to 5 mm 

 thick, and the central hollow nearly 2 cm in diameter. It was obvious that 

 there might be considerable quantities of the sponge buried in the mud, but 

 further efforts of collection were baffled by a storm, accompanied by wind and 

 violent rain, which broke at that moment. 



