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



size about 0"6 by 0"0126 mm. (2) Smaller, entirely spined styli (usually subtylostylote), 

 commonly a little bent towards the base and gradually sharp pointed ; length commonly 

 about O'l mm. but may reach up to 0*25 mm., thickness about 0*0066 mm. 



This is probably a common shallow-water species in the Cape Verde Islands. It is 

 remarkable on account of the high development of the Axinellid fibre and of the numerous 

 foreign bodies which the sponge contains. The latter character is probably due to the 

 nature of the bottom on which it lives. It is further distinguished by the presence of 

 the entirely spined styli. 



Localities. — St. Vincent, Cape Verde Islands ; shallow water. Three specimens. 



Harbour, St. Vincent, July 1873 ; depth, 7 to 20 fathoms. One specimen. 



Axinella {?) lunsecharta,^ Eidley and Dendy (PI. XXXVII. figs. 1, la, 2). 



1886. Axinella (?) lunxcharta, Ridley and Dendy, Ann. and Mag. Nat. Hist., ser. 5, vol. xviii. 



p. 481. V 



Sponge (PI. XXXVII. . figs. 1, 2) massive, sessile, subglobular. Size of largest 

 specimen about 38 by 31 by 25 mm., with a deep concavity on the lower surface. 

 A second specimen is about 21 mm. in diameter and attached to a small pebble. 

 Colour in spirit very pale yellow. Texture fairly firm, but compressible and rather 

 spongy. Surface uneven but glabrous, with numerous small, monticular eminences, 

 amongst which occur fewer but much larger eminences, volcano-like, each with a distinct 

 crateriform depression at the top, which is about 2 "5 mm. in diameter. (The degree of 

 development of these crateriform eminences differs in different specimens.) Pores C?). 

 Oscula minute, in the crateriform depressions (PL XXXVII. fig. la). 



Skeleton. — There is no special dermal skeleton ; the main skeleton is loosely 

 reticulate, consisting of primary lines of loose spiculo-fibre running vertically to the 

 surface and crossed by still looser and vaguer secondaries composed for the most part of 

 single spicules. The spicules in the main fibres are all, or nearly aU, directed towards 

 the surface of the sponge, but the Axinellid character of the fibre is barely recognisable. 



Spicules. — Megasclera; (l) smooth styli, more or less bent towards the base and 

 very gradually and sharply pointed; size about 0"4 by 0"014 mm. (2) Smooth oxea, 

 usually gradually sharp pointed at both ends, but very commonly with one end larger 

 and less sharply pointed than the other; size about 0"3.5 by 0'0126 mm. It is very 

 common in Axinellid sponges to find a few oxea along with the styli, but in this species 

 the oxea are abundant, though not so much so as the styli. The not uncommon tendency 

 which they exhibit towards blunting at one end seems to indicate that one form may be 

 derived from the other. 



1 So called from the resemblance which the surface of the sponge bears to a map of the moon, owing to the numerous 

 crateriform eminences. 



