258 A MONOGRAPH OF THE 



20. Halichondria Ingalli, Bowerbanh. 



Sponge. Sessile ; closely latticed by round or com- 

 pressed inosculating branches. Surface uneven, 

 slightly and minutely hispid. Oscula simple, nume- 

 rous, dispersed, minute. Pores inconspicuous. Dermal 

 membrane thin, pellucid, furnished with slender sub- 

 fusiform cylindrical spicula which are fasciculated, 

 forming a coarse and irregular network ; and rarely 

 with malformed bihamate, and angulated inequi-an- 

 chorate spicula. Sarcode abundant, gelatinous. Ske- 

 leton. Spicula attenuato-acuate, basally spined, and 

 rarely attenuato-acerate, medially spined. Intersti- 

 tial membranes furnished with dispersed, slender, 

 sub-fusiform, cylindrical spicula like those of the 

 dermal membrane. 



Colour. Nut-brown, alive. Dark brown when dried. 

 Habitat. About one mile off Castle Hill, Hastings, 

 J. S. Bowerbank, Moray Frith, Rev. Walter Gregor. 

 Exam in ed. Al i v e . 



The latticed form of this sponge approaches somewhat 

 to that of Chalina Montaguii, but the colour and surface 

 characters of the two species are so different as to cause 

 them to be readily distinguished from each other. The 

 rough and slightly hispid character of the surface in either 

 the fresh or dried state is apparent by the aid of a lens 

 of an inch focus, and beneath a power of about 100 linear the 

 latter character is seen to be produced by the protrusion 

 beyond the surface of the dermal membrane of portions of 

 the fasciculi of the skeleton. The larger oscula are barely 

 to be seen by the unassisted eye, and the greater portion of 

 them require the aid of a lens of an inch focus to render 

 them distinctly visible. The dermal membrane is furnished 

 abundantly with fasciculi of slender cylindrical or sub- 



