328 A MONOGRAPH Or THE 



axial lines, the same regularity of disposition does not 

 prevail. The slender acuate spicula of the interstitial 

 membranes are comparatively few in number, and so are 

 the inequi-anchorate and bihamate ones. Both the latter 

 forms are very difficult of detection in situ, even after a 

 section of the sponge has been mounted in Canada balsam ; 

 and it is only in the fragments of the membranes after 

 having been partially acted on by boiling in nitric acid, 

 that they are distinctly to be seen attached by the back of 

 tbe bow. They are not symmetrically arranged, but are 

 irregularly dispersed over the siu-face of the membrane. 

 The dentato-palipato-anchorate spicula are perfectly and 

 beautifully developed ; the distal palm extends to nearly 

 half the length oLthe spiculum, and the palm is wide 

 and symmetrical in shape. 



36. IsoDiCTYA PAUPEBA, Bowerbank. 



Sponge. Coating or parasitical; surface irregular, aspe- 

 rated. Oscula simple, dispersed, numerous. Pores 

 inconspicuous. Dermal membrane simple, pellucid ; 

 furnished with dispersed minute bidentate equi- 

 anchorate retentive spicula. Skeleton. Primary lines 

 multispiculous ; secondary lines bi or trispiculous ; 

 occasionally multispiculous ; spicula sub-fusiformi- 

 acuate, stout. Interstitial membranes. Spicula fusi- 

 formi-acuate slender; and bidentate equi-anchorate 

 retentive spicula like those of the dermal membrane. 



Colour. — Dry, light ochreous yellow. 

 Habitat — Torquay, Mrs. Griffiths. 

 Examined.— \^ the dry condition. 



I received thirteen fragments or specimens of this speciea 

 from my late friend, Mrs. Griffiths, of Torquay, the largest 

 not exceeding three fourths of an inch in diameter, and 

 about a quarter of an inch in thickness. The whole of the 

 specimens were much mixed up with e^^^raneous matter, 



