138 OKHAMANDAL MARINE ZOOLOGY REPORT PART II 



mesh of the network of fibrillar bands described above. They are the openings of deep 

 cylindrical canals of similar diameter, and probably represent true oscula. Between 

 them numerous smaller apertures, the openings of the inhalant canals leading from 

 the subdermal cavities, can be seen through the transparent dermal membrane. In 

 some places the soft tissues seem to have shrunk away from the skeleton, showing 

 the coarsely reticulate, dark-coloured, horny fibre projecting beyond the surface ; while 

 the pale-coloured growing points of the primary fibres appear in the conuli, supporting 

 the dermal membrane. 



The largest specimen (R.N. VIII.) is an irregular lobose mass about 100 mm. in 

 diameter. The texture (in spirit) is very soft and compressible, but resilient owing to 

 the coarse, stiff, horny skeleton. The colour in life (R.N. VIII.) was recorded as pink, 

 in spirit all three specimens are very pale grey. 



Of two specimens preserved in formalin (R.N. XXIX. 1) practically nothing re- 

 mained but the skeleton. 



The skeleton is a very coarse reticulation of dark-brown, almost black, horny 

 fibre. It is only occasionally possible to recognise main stems springing from points 

 of attachment. Indeed the abundant development of secondary connecting fibres 

 almost completely conceals any original tree-like growth there may have been, except 

 towards the surface, where branching main fibres terminate in the conuli. The con- 

 necting fibres are developed chiefly in the angles of the main branching system, with 

 the result that we can distinguish meshes of two quite distinct orders, large and small, 

 the small ones occurring in groups at the nodes of the reticulation formed by the large 

 ones. The large meshes average perhaps 5 mm. in diameter, the small ones, say, about 

 0-5 mm., but very variable. The thickest primary fibres measure up to about 0-34 mm. 

 in diameter and the thinnest secondary ones about 0-034 mm., between which extremes 

 all gradations occur. The fibres are entirely free from foreign inclusions and consist 

 of more or less numerous concentric layers of spongin. It is not possible to distinguish 

 sharply between the so-called pith and the surrounding spongin-lamellae, and, in spite 

 of the numerous descriptions in which such distinction is insisted upon, I believe that 

 this is frequently the case in the Aplysillidse. 



There is no dermal or subdermal reticulation of horny fibres. 



The canal-system is typically aplysillid. The flagellate chambers are very large 

 and thimble-shaped, measuring about 0-17 by 0-085 mm. Favourable sections show them 

 arranged in a single, much folded layer between the inhalant and exhalarit canals. 

 Each chamber has numerous prosopyles. 



Register Numbers, Localities, &c. II. 3, off Poshetra, January 7, '06 ; IV. 13, 

 off S.W. coast of Beyt Island ; VIII., Mangunda Reef ; XXIX. 1 (two skeletons), N. of 

 Poshetra, 3f-4 fms., 20.12.05. 



