132 CEYLON PEARL OYSTER REPORT. 



through a monaxonellid condition before finally disappearing, we may include the family 

 in the monaxonellid rather than in the tetractinellid grade, though, perhaps, logically 

 speaking, it ought to occupy a distinct grade of its own. The form of the micro- 

 scleres (when present) and the corticate character suggest a close relationship with 

 the Tethyidse. 



The family will always be historically interesting as having formed the subject ot 

 one of F. E. SCHULZE'S classical memoirs (40). 



Chondrilla, SCHMIDT. 

 Chondrosiidae with microscleres in the form of euasters of various kinds. 



Chondrilla australiensis, CARTER. 



1873, Chondrilla australiensis, CARTER (41) ; 1885, Chondrilla australiensis, LENDENFELD (42). 



The specimens of this sponge form thin crusts of a greyish colour (in spirit) and 

 irregular outline, spreading over masses of calcareous de"bris. One large specimen is 

 about 80 millims. in greatest breadth. The surface is smooth and sometimes 

 glabrous ; it may be minutely reticulate when seen under a lens, and in one specimen 

 (R.N. 185) it is very minutely papillate, with the spherasters so thickly aggregated 

 in the papillaB that they touch one another. The vents are minute and scattered. 



Having in my possession several of Mr. CARTER'S own microscopical preparations of 

 this species, evidently from the original types, I have been able to make a direct 

 comparison and to assure myself of the correctness of the identification. In both 

 Mr. CARTER'S and Professor HERDMAN'S specimens the spheraster, with smooth 

 conical rays, measures about 0'028 millim. in diameter, and the oxyaster, with 

 minutely spined rays, sometimes branched at the ends, measures nearly as much. In 

 a Ceylonese specimen I find that neither spicule is strictly confined to either the 

 cortex or the interior of the sponge, but while the spherasters are much more 

 abundant in the cortex, the oxyasters are much more abundant in the interior. 



It is noteworthy that Mr. CARTER has recorded (&) the occurrence of Chondrilla 

 nucula, the common European species, from the Gulf of Manaar. This species 

 appears to be of very wide distribution. 



RN. 17 (Gulf of Manaar); 185 (Donnan's Paar) ; 251 ; 376 (encrusting a shell of 

 Margaritifera vulgaris, Cheval Paar). 



Chondrilla australiensis, var. lobata, nov. 



This variety is represented by two specimens (apparently obtained together) which 

 differ conspicuously from the thin, encrusting form above described, being massively 

 lobose, with comparatively large vents placed singly on the top of the lobes. The 

 base of attachment is constricted to a few narrow projections on the lower surface, 

 and the entire body of the sponge exhibits a swollen, tumid appearance. The vents 

 measure up to 2 millims. in diameter, and each is surrounded by a thick, membranous 

 margin, which, in its turn, is usually surrounded by a shallow groove. The surface 



