224 CEYLON PEARL OYSTER REPORT. 



Aplysiua purpurea, CARTER. 



1880, Aplysina purpurea, CARTER (4); 1881, Aplysina purpurea, CARTER (65); 1889, 

 Aplysina purpurea, DENDY (3); 1889, Psammopemma fuliginosum, LENDENFELD, 

 pars (66). 



There is only a single dry specimen of this sponge in the collection, so that I am 

 not in a position to add anything to the descriptions of the species given by CARTER 

 and myself, except by referring back to some preparations of spirit material collected 

 by Mr. THURSTON, which show the sponge to be a true Aplysina and not, as 

 LENDENFELD has supposed, a Psammopemma. 



The skeleton is composed of dense local aggregations of very irregular, branching 

 and anastomosing horny fibres, accumulated along certain tracts to form the so-called 

 " compound fibres," while large intervening areas remain free from fibre altogether. 

 The fibres themselves have a very curious structure, consisting of a very thin outer 

 layer (if any) and a very thick " pith," the latter exhibiting a granular or often 

 minutely reticulate appearance. They are free from foreign bodies. The inhalant 

 pores are abundantly scattered over certain parts of the surface. The structure of 

 the soft tissues is very compact and the flagellate chambers are small and probably 

 aphodal or diplodal. In short, the canal-system probably agrees closely with that 

 described and figured by SCHULZE in Aplysina aerophoba, although the condition of 

 my material is not good enough to render a detailed comparison possible. 



LENDENFELD has, as already indicated, made the curious mistake of confounding 

 this species with " Psammopemma fuliginosum" a totally different sponge. CARTER'S 

 specimens of Aplysina purpurea were from the Gulf of Manaar and Trincomalee, but 

 he subsequently (65) identified an Australian sponge with the same species. Still 

 later, however, when describing his Pseudoceratina durissima (18), he showed that 

 the Austialian specimen previously identified by him as Aplysina purpurea should 

 really be considered as a specimen of Pseudoceratina durissima. LENDENFELD, 

 accordingly (66), in a manner very characteristic of that writer, observes that 

 " CARTER himself has shown that his Aplysina purpurea and his Pseudoceratina 

 durissima are identical," which, of course, is by no means the case. At the same 

 time he omits the locality from which the types of Aplysina purpurea were obtained 

 from the geographical distribution of Psammopemma fuli/jinosum, under which name 

 (while admitting that it is not the oldest) he also includes (rightly or wrongly) 

 CARTER'S Pseudoceratina durissima. 



Mr. CARTER has given a characteristic sketch of the external form of the sponge, 

 together with figures of the skeletal structure (65, Plate IX., fig. 1), which are 

 sufficient for the identification of the species. 



There can be no doubt that KELLER'S Psammaplysilla arabica from the Tied Sea (61) 

 is very closely related to, if not identical with, this species. The compound skeleton 

 fibres, consisting entirely (according to KELLER) of reticulate " Marksubstanz," the 

 cactiform surface, and black-violet colour in alcohol, all point to generic if not 



