128 THE SPONGES OF THE WEST-CENTRAL PACIFIC 



cs 



rid 



Texl Figure No. 80. Spicules of Tcdania oligostyla, X 781. A: Tylote from the ccto- 



some; the entire spicule is shown, but in two parts. B: The head only of one of the rare 



endosomal styles. C: Larger microspined raphide. D: Microspined raphide. 



wading at Ebon Atoll from the Pearl Pool in the western portion of the 

 lagoon. The depth was low tide mark, and the substrate was dead coral. 



The species was extremely common in this portion of Ebon Atoll. 



The shape may be described as interstitial, because the sponge grew in 

 spaces between fragments and masses of dead coral, extending indefinitely 

 in all directions but not protruding to any great extent. In places there 

 appear to be masses of the sponge as much as 10 cm in diameter, but these 

 masses consist chiefly of dead coral with only a sort of cement or glue of 

 the sponge tissue. 



The color in life was bright red, but the endosome was definitely paler 

 than the ectosome. The consistency was weakly spongy, very fragile. 



The surface is smooth, but micro-punctiform, with pores which in life 

 were more than 200 /x in diameter but which close upon dying. There are 

 about two of these pores per each square mm. The oscules are very few, 

 but as large as 8 mm in diameter and are characterized by a raised rim 

 2 to 4 mm high. 



The ectosome is characterized by more densely protoplasmic structure 

 and brighter color than the more cavernous endosome. The latter is some- 

 what like wet breadcrumbs, as is characteristic of the genu.? Tedania. 



The skeleton includes very straight tylotes, 2.5 /x by 220 /x, with heads 

 about 3 ix or 3.5 fi in diameter and faintly microspined on the apices. Such 

 dermal spicules are fairly common in the genus Tedania, although it is to 

 be expected that they would be strongyles rather than tylotes. In this Tedania 

 from Ebon Atoll, such spicules instead of being confined to the ectosome 

 are also very common in the endosome. Here one would expect to find 

 smooth styles ; and, after long and careful search, a few such were discovered, 

 but they are very rare. They are 3.5 ju, by 240 p in measurement. The micro- 

 scleres are quite typical of nearly every species of the genus Tedania. They 

 are called onychaetes, and are essentially raphides, or microxeas, but very 

 long. Dimensions in this specimen were 0.5 xt by 75 ju. to 1.5 /a to 175 it. 



