50 E. KIRKPATEICK. 



OCEANAPIA TANTULA.* 



(Plate XVIII., figs. 5, 5a, 5b, and Plate XXIV., fig. 8a-e^) 

 1907. Oceanapia tantula Kirkpatrick (10a. p. 289). 



Description. — The sponge consists of five small fragments of tubes, the longest of 

 which is 8 mm. in length, by 4 mm. in diameter ; three of the pieces are hollow, thin- 

 walled and tubular ; the other two are solid. One of the solid pieces seems to belong 

 to the top of a fistula. 



The colour is transparent white. 



Skeleton. The dermal layer is composed of a chitinons-looking membrane with 

 strongyles lying tangentially, usually in one layer and densely packed, but sometimes 

 more or less scattered. 



The white strands of the loose subdermal reticulum are visible through the sui'face. 

 They are longitudinal, and only anastomose occasionally. The strands are less than 

 • 1 mm. in diameter. They vary in composition ; in some parts being composed of 

 strongyles smaller than those of the dermal layer, in other parts of smooth tricho- 

 dragmata, or again of strongyles, amphityles and trichodragmata. The pale transparent 

 choanosomal tissues are crowded with small spined rhaphides. 



Spicules. Megascleres. Strongyles, 437 x 19 /a, slightly fusiform, curved once 

 or sometimes twice. Occasionally one end is pointed, the spicule becoming 

 a style. 



Amphityles, 395 x 7 "25 /a, slightly fusiform, heads 13 /a long, 9*75 mm. 

 broad. 



Microscleres. Long, smooth raphides, separate or in bundles forming part of the 

 subdermal reticulum, 650 x 2 • 5 /u,. 



Short scattered spined raphides, usually stylote, 162 /n long, and about 2 ■ 5 m broad. 



H. V. Wilson describes (34. p. 128) a species of Oceanapia, viz. 0. bacilli/era 

 with strongyles, but it has the usual sigmata. 



Oceanapia (Phloeodictyon) singaporensis (Carter) has strongyles in the dermal 

 layer, but oxeas as well as strongyles in the skeleton fibres, and there are no micro- 

 scleres. 



The species of the Gelliine genus Rhapliisia have oxeas, trichodragmata, and, in 

 one species, toxa ; but there are no fistulae, and there is no subdermal reticulum of 

 spicular fibres. 



It is regrettable that there is so small an amount of material on which to base a 

 new species, but the marked characters of that which is available seem to render 

 such a proceeding justifiable. 



Dredged near Winter Quarters, from No. 10 hole, 130 fms. 



* Tantulus, ever so little. 



