228 CEYLON PEARL OYSTER REPORT. 



RN. 158 (Stat. LXIV., 5 fathoms, south-east of Modragam, March 17, 1902); 

 158A (south of Cheval); 380 and 381 (both from Cheval Paar, March 4, 1902). 



ORDER 2 : HETEEOCCELA. 



Calcareous sponges in which the collared cells are confined to more or less well-defined 

 flagellate chambers. 



FAMILY: GRANTIID^E. 



Heterocoela with a distinct and continuous dermal cortex, completely covering over 

 the chamber-layer and pierced by inhalant pores. There are no sub-dermal 

 sagittal triradiates, nor conspicuous sub-dermal quadriradiates. The flagellate 

 chambers vary from elongated and radially arranged to spherical and irregularly 

 scattered ; while the skeleton of the chamber layer varies from regularly articulate 

 to irregularly scattered 



Leucandra (HAECKEL). 



Grantiidse in which the flagellate chambers are spherical or sac-shaped, never 

 arranged radially around the central gastral cavity, with which (or with the 

 main exhalant canals derived therefrom) they communicate by a more or less 

 complicated exhalant canal-system. The skeleton of the chamber layer is 

 composed of irregularly scattered radiate spicules, but it may still present traces 

 of its derivation from a radially symmetrical type in the presence of a few sub- 

 gastral sagittal triradiates. 



Leucandra donnani, n. sp. Plate XIII., fig. 10. 



The only specimen in the collection consists of a single Leucon person of sac-like 

 form ; elongated, sub-cylindrical, but slightly compressed ; rather strongly curved ; 

 tapering gradually from broadly rounded base to narrower apex, Avhere the terminal 

 osculum is situated. The outer surface is nearly smooth, but slightly granulated in 

 appearance. The osculum has no spicular fringe, but a slightly developed mem- 

 branous margin. The total length of the specimen is 23 millims. ; the maximum 

 diameter at the base is about 9*5 millims., and the diameter of the vent is 2 millims. 

 The thickness of the sponge-wall in the middle is about 2 millims. The colour (in 

 spirit) is light brown and the texture firm but brittle. 



The dermal cortex, of sagittal triradiates, is only about 0'05 millim. thick; beneath 

 it lie large, irregular sub-dermal cavities, without, however, any special supporting 

 skeleton of their own. The gastral cortex, of sagittal quadriradiates, is about as 

 thick as the dermal cortex and pierced by the numerous apertures of the exhalant 

 canals. The skeleton of the chamber layer consists for the most part of very large 

 sagittal triradiates, generally arranged with the basal ray pointing outwards. 



