REPORT ON THE MONAXONIDA. 



97 



spicule, the amphiaster ; the additional spicules being arranged in a dense external layer. 

 Or, on the other hand, it may have been derived from a genus of sponges, characterised 

 by the presence of an amphiaster, which, having taken to deep water and a soft bottom, 

 has acquired the " Crinorhiza " form independently. In any case the genus seems 

 to be very nearly related to Cladoi-hiza, standing to it in much the same relation 

 as Meliiderma does to Clwndrocladia (vide p. 102). 



Axoniderma mirahile, Eidley and Dendy (PL XX. fig. 5 ; PI. XXI. figs. 8, 9, 10). 



1886. TrocJwderma mirahile, Eidley and Dendy, Ann. and Mag. Nat. Hist., sen 5, vol. xviii. 



p. 344. 

 1886. Axoniderma mirahile, Ridley and Dendy, Ann. and Mag. Nat. Hist., ser. 5, vol. xviii. 



p. 493. 



Sponge (PI. XX. fig. 5) of " Crinorhiza " form, consisting of a conical, cap-shaped 

 body perched on the end of a slender stalk or root, which is inserted into the centre of 

 the lower, concave surface of the body. The root sweUs out considerably just before 



Fig. 5.—Axonidenna mirabile. Vertical section, showing tlie skeleton arrangement ; a, axis of stem ; 

 a', axis of supporting process ; c, cortical layer ofamphiasters ; ch, clioanosome (?). x 5. 



its insertion into the head. From the free circular margin of the body numerous 

 (thirty or forty) very long, filamentous, spicular processes are given off" obliquely 

 outwards and downwards. The summit of the body is produced into a papilla, from 

 which project numerous very short and slender spicular processes. Transverse diameter 

 of the body, from base to base of the long spicular processes, a httle over 6 mm. 

 Length of root nearly 50 mm.; it thins out to hair -like proportions at the lower end, 

 and may very possibly have been broken off". Length of the long spicular processes 

 (zooL. CHALL. EXP. — PAKT Lix. — 1887.) Nnu 13 



