COLLECTED BY THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 445 



diameter of 0'021 mm. (2) Acanthostyli echinating the fibres. — Straight or slightly 

 curved shaft with characteristically arranged spines as described and figured by 

 Ridley and Dendy (15), for a sponge recorded as a variety of Vosmaer's species. 

 The head is thickly spined, with the spines on its sides directed towards the pointed 

 end of the spicule. Then follows a space usually free from spines. The remainder of 

 the spicule is thickly spined, with the points of the spines directed towards the head 

 of the spicule. Length 0-13-0-16 mm. by 0-01-0 - 013 mm. (3) Slender styli, 

 straight, with minutely spined head, forming the dermal brushes of spicules and 

 scattered through the sponge. They are somewhat varying in length, being usually 

 between 0'15-0'28 mm. by 0'005-0'008 mm. (4) Isochelse palmatse. — Numerous, 

 very minute, scattered through the sponge. Length about 0'008 mm. (5) Toxa. — 

 Numerous, scattered through the sponge. The ends are spined and there is a strong 

 curve in the middle of the spicule. From exceedingly minute to about 0'175 mm. 

 in length, with a thickness of 0'0025 mm. 



Through the kindness of Professor Vosmaer, I have been able to compare the 

 Scotia specimen with fragments of the original specimens, a preliminary description 

 of which has alone been published (26). As far as can be seen from a study of 

 the dried fragments the arrangement of the skeleton is identical, except that in 

 both of Vosmaer's specimens numerous sand grains are incorporated with the 

 skeleton. The spicules are exactly similar as to shape, but there are slight 

 differences as regards their measurements. The dermal spicules are alike both 

 in size and character, but the large, smooth styli, though alike in shape, are, on the 

 whole, a little shorter in the original specimens, in which they vary between 

 0'2-0'26 mm. Their maximum diameter is the same, namely, 0'021 mm. The 

 acanthostyli are, as a rule, slightly shorter in one of the specimens, being O'l 1—0*14 

 mm. in length. In the other specimen they are about the same as in the Scotia 

 sponge. The microscleres are exactly similar in all three specimens. 



Though differing in external appearance from the specimen described by 

 Ridley and Dendy (15) under the name Rhaphidophlus lobatus (Vosmaer) var. 

 horrida, the arrangement of the skeleton is similar and the spicules of both agree 

 exactly, except that in this case, too, there are slight differences in their measure- 

 ments. The smooth styli are rather longer and thicker in the Challenger specimen, 

 and the characteristic acanthostyli, which are identical in shape, are very slightly 

 longer than in the Scotia specimen. 



With the possible exception of one of the original specimens of which the 

 locality is not known, the specimens of this species hitherto obtained have been 

 collected in the neighbourhood of the Cape of Good Hope. 



Clathria rhaphidotoxa n. sp. (Plate XXXVIII, fig. 2 ; Plate XL, fig. 15.) 



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

 specimens. 



