130 CEYLON PEARL OYSTER REPORT. 



impossible to suppose that the two are identical. Both belong, however, to Topsent's 

 third division of the genus Cliona. 



Thiele's Cliona concharum (39), from Japan, perhaps comes nearer to our species 

 than any other, at any rate so far as the spiculation is concerned, the differences in 

 this respect being so slight that subsequent researches may make it desirable to 

 consider the two as being only varietally distinct. In the Japanese form, however, 

 the chambers excavated by the sponge seem to be much smaller, while the spined 

 microxea are a good deal longer (0*09 millim.), than in that from Ceylon. 



Carter's Cliona warren i (5), also from the Gulf of Manaar, on the other hand, is 

 a very different species., and, according to Topsent (37), is identical with the European 

 Cliona celata. 



R.N. 261 (Gulf of Manaar very abundant, and destructive, on the pearl banks). 



Family : SUBERITf D,E. 



Astromonaxonellida in which the megascleres are styli or tylostyli, and the microscleres 

 have completely disappeared. 



Suberites, Nardo. 



Suberitidaj of varying form, but without mammiform projections on the surface. 

 Spicules tylostylote (nearly always). Skeleton usually arranged radially, with 

 surface brushes of spicules smaller than those of the main skeleton. 



The genus Suberites, at any rate so far as its typical species are concerned, for it 

 may possibly be of polyphyletic origin, is, as I have already indicated, probably 

 derived from Sjyirastrella by loss of the spirasters. Carter even admitted into the 

 genus certain species with spirasters. 



It is remarkable that there is only one species of the genus, and of that only a 

 single specimen, in the present collection. In making my preliminary examination in 

 Liverpool (which had to be done very hastily), I identified one of the specimens as 

 Suberites inconstans, var. digitata, a form jjreviously described by me from near 

 Ceylon, but more careful examination subsequently revealed the presence of spirasters 

 and thus proved that the specimen was really a Spirastrella. 



Curiously enough, Thiele (39) has come to the conclusion that Suberites inconstans 

 is in reality a Spirastrella in' which I have overlooked the spirasters, these being, 

 according to him, small and scarce. This is, of course, possible, but it is by no means 

 proved. Thiele has apparently never seen specimens from Ceylon or India, but 

 identifies certain specimens from Celebes with the species, under the name 

 Spirastrella inconstans. Unfortunately I am unable to re-examine the types of the 

 species here in South Africa, as the original specimens and preparations remained in 

 the British Museum. 



Topsent has sub-divided the old genus Suberites into a number of separate genera, 



