19I5.| N. ANNANDALE: Parasitic Sponges. 467 
ter’s figure the amphioxi are shown as having a regular curve, 
but this is by no means always the case and though they are not 
swollen in the middle they are often distinctly geniculate at or 
near that point. With Dendy’s redefinition of Sfongosorites the 
species agrees precisely. All this is made abundantly clear when 
A. excavans is compared with the form here described as A. exca- 
vans var. digitifera. 
The genus Amorphinopsis may now be redefined as follows :— 
Axinellidae of encrusting, reticulate or massive shape, some- 
times bearing upright branches or conuli; the skeleton 
composed of stout spicule-fibres containing little horny 
material and forming a coarse and irregular reticulation. 
The fibres consist of large, smooth styli or amphioxi, or of 
a mixture of smooth styli and amphioxi, lying parallel to 
one another. Smaller spicules of the same types surround 
the fibres and as a rule form a horizontal layer in the 
ectosome. Some or all of the spicules are geniculate in 
the middle; sometimes they are also inflated at this 
point. 
Amorphinopsis excavans, Carter. 
1887. Amorphinopsis excavans, Carter, op. cit., p. 77, pl. v, figs. 12-15. 
The sponge in Carter’s specimen consists of a thin external 
crust and a network of fine cylindrical basal branches that ramify 
in the excavations of Clionidae in dead coral. The external crust 
is remarkable for the curious little prominences or bosses with 
which it is ornamented and for the strands of spicules that radi- 
ate from them. The regularity of their arrangement is somewhat 
exaggerated in Carter’s figures. The prominences seem to me 
to be no more than incipient, or possibly abortive, conuli or 
branches. Each probably contains an osculum obliterated by con- 
traction. There is a dense external covering of smaller spicules 
lying horizontally and matted together on the surface of the sponge. 
The internal or basal branches rarely contain more than a single 
stout strand of spicules, but they ramify and anastomose in accord- 
ance with the ramifications and anastomosings of the cavities they 
occupy. A horizontal reticulation of fibres occurs near the surface. 
The spicule-fibres, whether on the surface or inside the coral, 
consist mainly of the larger spicules, which are for the most part 
true amphioxi. Occasionally a slender sub-stylote spicule is to be 
found amongst them, while a comparatively large number of true 
styli are also present. The last are asstout as the stoutest amphi- 
oxi, but usually shorter. All the amphioxi are more or less curved 
and most are crescentic in form; a few are, however, distinctly 
geniculate at or near the middle and forms (which must be re- 
garded as mere abnormalities) may be found in which there is a 
regular angle near one end. 
The smaller spicules, which surround the fibres in an irregular 
manner as well as forming a layer on the surface of the sponge, 
comprise both amphioxi and styli. ‘The former resemble the 
