COLLECTED BY THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 441 



The species appears to have a wide geographical and bathymetrical range. It 

 has been recorded off La Calle, Algeria (21 ) ; off the Azores, 1250 metres (22) ; and 

 it was dredged by the Ingolf at a number of stations in Denmark Strait, off the 

 south of Iceland and east of the Faroe Islands, at depths varying between 76 and 

 691 fathoms (13). Hentschel (9) describes a variety of the species for Shark's Bay, 

 South-West Australia, in 6-9 metres. 



Hymedesmia parva n. sp. (Plate XL, fig. 14.) 



Station 482. Houtjes Bay, Saldanha Bay, shore. 19th May 1904. 



Sponge forming a very thin encrustation on both inner and outer surfaces of a 

 large dead Patella shell. 



The thickness of the sponge is about 0'2 mm. ; the surface is finely hispid. 



The main skeleton consists of acanthostyli, closely crowded together and standing 

 vertically with their heads on the substratum. The longer project very slightly 

 beyond the surface of the sponge. The dermal skeleton consists of tornota lying 

 horizontally to the surface. They occur singly, or sometimes a few lie loosely 

 together, but they do not form well-defined bundles. Some of the tornota lie 

 horizontally to the surface at different levels through the sponge. 



Spicules. — (l) Acanthostyli, which are divided into two groups. — The longer 

 are straight or slightly curved, and taper evenly from the base to a fairly sharp 

 point ; the head is covered with numerous, fairly strong, blunt spines, and a few 

 very small spines are scattered for some distance along the shaft, leaving the upper 

 part smooth. These spicules are fairly uniform in size, and measure 0'15-0"2 mm. 

 in length by O'Ol mm. The smaller acanthostyli are very similar in shape to the 

 above, but are spined along their whole length. They measure 0'075-0'l mm. by 

 0'006-0'008 mm. (2) Tornota. — Very slightly swollen at the ends, which terminate 

 in a point; 0'1-0'15 mm. in length by 0'0025 mm. (3) Isochelse arcuatse. — These 

 are abundant throughout the sponge and in the dermal membrane. They are 0'02- 

 0'027 mm. in length, with a rather strongly curved shaft about 0"003 mm. in 

 diameter. Very small chelae of a similar shape, but only about '01-0 "01 5 mm. in 

 length, are present in numbers. (4) Sigmata. — These are abundant throughout the 

 sponge and in the dermal membrane. They are 0'02-0'035 mm. in length, with a 

 maximum thickness of 0'0025 mm. 



Microciona similis n. sp. (Plate XL, fig. 6.) 



Station 482. Houtjes Bay, Saldanha Bay, shore. 19th May 1904. One 

 specimen. 



Sponge forming an encrustation, about 0'45 mm. in thickness, on a small stone. 



The surface is hispid, and the colour in spirit is pale greyish yellow. 



The main skeleton consists of short, unbranched, plumose fibres, about O'l mm. 



