186 THE VOYAGE OF H.M.S. CHALLENGER. 



Percival Wright,' who dredged Ilyalonema lusitanicum from a depth of 480 fathoms 

 south-west of Setubal, and had observed it in the fresh condition, found it emljedded 

 in mud up to that part of the siliceous spicular tuft which was not covered by Palythoa, 

 while the upper extremity of the tuft bore a sponge body with several oscular openings. 

 In the polypes forming the crust of the stalk movements of the tentacles were observed. 



Hyalonemas were dredged in a similar situation in the Gulf Stream by Wyville 

 Thomson from a depth of 550 fathoms. 



In his memoir on Holtenia carijenteri,- Wyville Thomson refers to a Hyalonema 

 loveni as a new species, without however describing or characterising it. 



Percival Wright^ now described in an elaborate paper the Hyalonema found off the 

 coast of Portugal by Barboza du Socage, Wyville Tliomson and himself, and named it 

 Hyalonema mirabile. On a specimen with an oval cup-shaped body, about 8 inches in 

 length and 4 inches in breadth, " a number of irregular large openings (oscula) " could 

 be seen in an upper pitting, and these " are covered over with a delicate open sarcode 

 network, the edges of the meshes of which are thickly lined by the spicules called 

 'spiculate cruciform spicules' by Bowerbank." A figure of this, given on his pi. iii., 

 shows the sieve-net on the upper truncated surface of the sponge body, extending 

 evenly over the oscular opening and over the layer of the " spiculate cruciform spicules " 

 in the net beams. 



The two sponges described by Sars in 1872, in his work "On some remarkable 

 forms of animal life from the great deeps ofi" the Norwegian coast," and named as 

 Hyalonema longissimum and Hyalonema parvum, manifestly do not belong to the 

 Hexactinellida any more than his Hyalonema horeale. 



In the work entitled Depths of the Sea, Wyville Thomson reported in 1873 on 

 some Hyalonemata which he had dredged to the north of the Butt of Lewis from a depth 

 of 450 to 500 fathoms. In these the root-tuft alone measured 40 cm. or more. He 

 identified these forms as Hyalonema lusitanicum, Barboza du Bocage, and figured {loc. 

 cit, p. 421) a slender specimen about 34 cm. in length. It is noteworthy that this figure 

 does not include the sieve-net which was observed l^y Percival Wright in his Portuguese 

 specimen (described under the title Hyalonema mirabile), covering the oscular openings 

 of the upper truncated surface. Instead of this a central conical boss projects about 

 2 cm. above the upper bounding surface, which is provided with large openings. 



Higgin next described, in 1875,* a Hyalonema from Zebu (one of the Philipijine 

 Islands) as Hyalonema cehuense. This form resembles, indeed, in many respects the 

 Japanese Hyalonema sieboldii, but according to Higgin's description and figures differs 

 from that species chiefly in the following points : — the form of the body resembles that 

 of a hewer's mallet ; the polype crust of the stalk is absent ; the " large stout acerate 



1 Arm. and Mag. Nat. Hist., ser. 4, vol. ii. p. 323. ^ Phil. Trans., p. 701, 1869. 



3 Quart. Joum. Micr. Sci, p. 73, 1870. * Ann. and Mag. Nat. Hist., ser. 4, vol. xv. p. 377. 



