REPOKT ON THE MONAXONIDA. 177 



The spiculation is distinguished by its plasticity, the different forms of linear spicules 

 appearing to run into each other, and to have little constancy within the genus ; species 

 are, however, separable by the forms and proportions of their spicules. An elongated 

 flexuous form is fairly constant. 



Acanthella pulcherrima, Ridley and Dendy (PL XXXII. fig. 3). 



1884. Acanthella sp., Eidley, Zool. CoU. H.M.S. "Alert," Brit. Mus., 1884, p. 463. 



1886. Acanthellax>ulchernma, Ridley and Dendy, Ann. and Mag. Nat. Hist., ser. .5, vol. xviii. p. 479. 



This species was obtained by the "Alert" and described by Eidley {loc. cit.) without 

 a name and vv^ith no figures. We have decided to quote the original description and to 

 add a figure of the very characteristic external form (PI. XXXII. fig. 3). 



"Externally resembling Spongia carduus, Lamarck (Ann. Mus. Hist. Nat. xx. p. 381). 

 When guided by the description alone, I had referred the present specimen to this species 

 with more confidence than usual ; but on mounting sections of the probable type 

 specimen at Paris, I saw that it was a different species. The points in which the 

 description does not cjuite suit this form are "pedicule cylindrace, tres-dur," the stem 

 having apparently been flattish, and, though stiff, not inflexible ; and " couleur d'un 

 blanc grisatre," whereas this (in spirit) is flesh-colour. The ridges run longitudinally up 

 and down the sponge, and are 1 to 3 millims. high, and their free edge is beset with 

 sharp (in spirit flexible) points at intervals of one or two millimetres. Texture tough 

 and flexible, substance compact, surface between inequalities glabi'ous. It is a true 

 Acanthella. The spiculation is as follows : — (l) Smooth acuate, slightly curved, tapering 

 gradually to a sharp point, about "4 to '6 millim. by -0095 niillim. (2) Smooth undula- 

 ting cylindrical with rounded ends, length about "7 millim., diameter just '0063 millim. 



" The species differs from the Adriatic forms, A. acuta and ohtusa, Schmidt, in the 

 broad explanate form and in the smaller size of the spicules, the cylindrical being much 

 shorter and thinner, the acuate much shorter than in those species. The skeleton forms 

 a loose-fibred Axinella-like network of spicules, imbedded in a dense, transparent, almost 

 colourless mass of caoutchouc-like consistency, containing nucleoid bodies about "007 to 

 "008 millim. in diameter. 



''■ Hab. Prince of Wales Channel, Torres Straits, 7 fms. A single specimen in 

 spirit, 35 millim. (1| inch) high by 29 millim. across." 



As regards spiculation we must further add that an unequal-ended oxeote spicule is also 

 common, of about the same size as the stylus. This is a remarkably pretty sponge. The 

 Challenger obtained one specimen (PI. XXXII. fig. 3), measuring about 56 mm. in height 

 and 46 mm. in breadth ; it is based upon an agglomeration of Polyzoa, fragments of 

 barnacles, &c., and is a very much finer example than that obtained by the "Alert." 

 Locality. — Cape York, Torres Strait; depth, 3 to 11 fathoms. 

 Habitat. — Torres Strait (" Aleit," Challenger). 

 (zool. chall. EXT. — PART Lix. — 1887.) Nnn 23 



