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



may be added ; we are thus able to reduce its bulk very considerably, but even thus 

 limited the genus is not a natural one. 



Esperiopsis, Carter, as emended by us (above, p. 76) forms a natural genus which 

 we have felt able to remove from the general mass of such sponges as Vosmaer unites 

 under the name Amphilectus, and as our knowledge of the Desmacidonidce increases it will 

 no doubt become necessary similarly to detach other groups. 



Amphilectus apollinis, Ridley and Dendy (PL XIX. figs. 3, 3a, 3i, 3c). 



1886. Amphilectus apollinis, Kidley and Dendy, Ann. and Mag. Nat. Hist., ser. 5, vol. xviii. p. 350. 



Sponge massive, amorphous, cavernous. The largest specimen is oval, cake-shaped ; 

 about 50 mm. long by 38 mm. wide and 19 mm. thick. Colour in spirit light greyish- 

 yellow. Texture rather soft and spongy. Surface very uneven, deeply folded, slightly 

 glabrous in places where the dermal membrane remains uninjured. Dermal memhrane 

 fairly distinct. Oscula (?).^ 



Skeleton. — (a) Dermal; in some parts there is a very distinct, but confused, dermal 

 reticulation of slender stylote spicules, while in other parts this appears to be scarcely 

 represented, (b) Main; a confused Halichondrioid reticulation of stout, stylote spicules. 



Spicules. — (a) Megasclera; of one kind only, but of two distinct sizes. (1) Stout, 

 slightly curved, smooth styli (PI. XIX. fig. 3), size about 0"5 by 0"0168 mm.; making 

 up the main skeleton. (2) Slender, straight styli (PI. XIX. fig. 3a), very sharply and 

 gradually pointed, often very slightly spined at the base and with a slight tendency to 

 become tylostylote; size about 0*315 by 0'0063 mm., almost entirely confined to the 

 dermal layer. (6) Microsclera; of two kinds — (l) small palmate isochelge (PI. XIX. 

 fig. 3c); length about O'OIS mm.; very abundant. (2) Large toxa (PI. XIX. fig. 36), 

 of very beautiful form and with spined ends, size of the full-grown spicule about 0'3 by 

 0'0045 mm.; very abundant ; the specific name has reference to them. 



Vosmaer ^ has founded a genus Artem,isina {vide supra) of which the most characteristic 

 spicule is a toxite with spined ends ^ like that which occurs in Amphilectv^ apollinis. 

 Possibly the two species Artemisina suberitoides, Vosmaer, and Amphilectus apollinis, 

 nobis, come near to one another and may even belong to the same genus, but they difi"er 

 very widely in the texture of the sponge, and our present species possesses an 

 additional form of megasclera (viz., the slender stylus with spined base) not present in 

 Artemishia. 



The presence of spined toxa, taken alone, is certainly not a character of generic 

 importance, for such spicules occur in several species that are widely distinct from one 



1 Both specimens are infested by very numerous small Amphipoda which live just below the surface, often causing 

 it to be deeply pitted, but these pits must not be mistaken for oscula. 



2 Sponges of the "Willem Barents" Expedition, 1881-82, p. 25. 3 loc. ciL, pi. v. fig. 51. 



