COLLECTED BY THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 455 



A large series of specimens of this species was obtained, about twenty-five small 

 specimens from 2-24 mm. in height, and about thirty-nine larger specimens, some of 

 which are over 100 mm. in height. The latter vary a good deal in external appear- 

 ance. Some of them are quite Siphonochalina-like, consisting as they do of upright, 

 rounded tubes, free except at the base, or more or less coalescent throughout their 

 length, with a large osculum at the summit of each tube. Others consist of upright, 

 flattened branches bearing a row of small oscula round the margins, and closely 

 resembling Homceodictya palmata (Johnston) in external appearance. Others, again, 

 have more or less coalescent flattened branches, with numerous small oscula scattered 

 chiefly over one surface, as well as along the edges of the branches, or they possess 

 fewer, but larger oscula. Some of the specimens consist of fan-like lobes with 

 numerous oscula along the margins, while two form thick encrustations on sea-weed, 

 and possess numerous oscula. In a "few specimens, part of the sponge consists of 

 Siphonochalina-like tubes, while the remaining part consists of branches bearing 

 small oscula. The specimen figured (PI. XXXIX, fig. l) has somewhat this shape. It 

 is growing on a large specimen of Myxilla simplex (Baer), to which it is attached in 

 two places. It rises to a height of 112 mm., and possesses several tubes about 

 13-16 mm. in diameter, which are more or less coalescent. A branch is given off 

 nearly half-way up these tubes, which is attached to another part of the supporting 

 sponge, over which it spreads as a thin encrustation bearing numerous oscula. From 

 this part arise two branches, the more complete of which has small oscula along the 

 margin, and which consists apparently of small coalescent tubes. The oscula are 

 about 7 mm. in diameter on the more Siphonochalina-like part of the sponge ; on the 

 other part they vary from 1-4 mm. in diameter. 



The young specimens are growing on colonies of a Sertularella. They vary in 

 size from 2 mm. in height by 1 mm. to 24 mm. in height by 8 mm. The smaller of 

 these are somewhat oval, and are compressed from side to side, with a single osculum 

 at the summit, or with several oscula. The larger are finger-like, sometimes with a 

 well-marked stalk, occasionally cylindrical, but usually more or less compressed. 

 There is a fairly large osculum at the summit, or a row of smaller oscula along the 

 margin. They are, for the most part, unbranched, but one of the largest of these 

 young specimens gives off a branch bearing a terminal osculum. Some of these 

 young sponges are extremely like small specimens of Siphonochalina in external 

 appearance. Next in size to these small specimens is one 45 mm. long with a 

 greatest breadth of 10 mm. It is much compressed, and bears several oscula along 

 its edge. The largest specimen in the collection is about 100 mm. in height, with a 

 breadth of 125 mm. It consists of a number of fiat, more or less coalescent, fan-like 

 lobes, with numerous oscula along their margins. It contains many embryos, the 

 older of which are crowded with short, slender oxea. 



The surface of all these specimens is even, but it is minutely hispid from the 

 projecting ends of the main skeletal fibres. The oscula are on a level with the 



TRANS. ROY. SOC. EDIN., VOL. L, PART II (NO. 15). 64 



