COLLECTED BY THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 457 



although showing the characteristic bending of the axis, they are quite different in 

 shape from those of Homceodictya palmata. 



Homceodictya alata n. sp. (Plate XXXIX, fig. 5 ; Plate XL, fig. 13.) 



Station 482. Reit's Bay, Saldanha Bay, shore. 21st May 1904. One small specimen. 



Station 483. Entrance to Saldanha Bay, 25 fathoms. 21st May 1904. Two specimens. 



Three specimens are in the collection. The largest is an irregularly oval mass 

 about 42 mm. thick, with broad, wing-like expansions on either side formed by 

 flattened anastomosing branches. The whole sponge measures about 160 mm. in 

 diameter by 95 mm. There is no sign of its having been attached to any support. 

 The remaining specimens are very much smaller and are incomplete, but they have 

 a similar external appearance. The surface is slightly papillose, and, under the lens, 

 it is seen to be finely hispid. The oscula are not numerous. They are small, 

 round and scattered, and are about 1—1*5 mm. in diameter. The pores are scattered ; 

 the largest measured reached a diameter of 0*15 mm. The consistence is firm, but 

 slightly compressible. 



The colour in spirit is pale greyish yellow. 



The main skeleton is an irregular reticulation of fibres. The principal fibres are 

 strong bands of multiserially arranged oxea. They run upwards through the sponge 

 and branch. At the surface they end in densely set vertical brushes of spicules, which 

 pierce the dermis. The transverse fibres connecting the principal ones are ill-defined, 

 and consist of single spicules, or of a few spicules lying loosely together. Numerous 

 scattered oxea occur through the sponge. There is no special dermal skeleton. 



Spicules. — (l) Oxea, rather abruptly pointed and usually slightly crooked. 

 They measure 0*3-0*425 mm. in length by 0*01-0*015 mm. (2) Isochelse arcuatae. — 

 These microscleres occur in abundance through the sponge and in the dermal 

 membrane. They have a slender, slightly curved shaft and short teeth, and they 

 are very similar in appearance to the chelae of Homceodictya ramosa (15, pi. xxiii, 

 fig. 4 a and b). Length 0*016 mm. 



This species approaches Homceodictya ramosa (Ridley and Dendy) of the 

 Challenger Expedition (15) in its spiculation, but differs from it in external appear- 

 ance and in the arrangement of the skeleton. The oxea, too, are much longer 

 in the Challenger species and are, on the whole, about twice as thick as in 

 the new species. 



Family Haplosclerid^e. 



Siphonochalina tubulosa (Esper). (Plate XL, fig. 10.) 



Station 478. Table Bay, shore. May 1904. Three large specimens. 

 Station 482. Saldanha Bay, 5 fathoms. 20th May 1904. One small specimen. — 

 Reit's Bay, Saldanha Bay, shore. 21st May 1904. Fragments. 



