ISODICTYA. 153 



portions of the interstitial membranes several very 

 minute bihamate spicula dispersed on the dermal 

 membrane. They are very minute, slender, and 

 require a power of at least 300 linear to render them 

 distinctly to the eye. I did not detect this form of 

 retentive spiculum in either of the specimens of the 

 species previously examined." 



65. ISODICTYA FIMBRIATA, Bow., IT, 337 ; in, PL LVIII, 

 figs. 714. 



1861 Halichondriafimbriata, Bowerbank. List Brit. Marine 



Invert. Fauna (Brit. Assoc.), p. 69. 

 1861 Tereus finibriatus, Gray. Proc. Zool. Soc., p. 537. 



This interesting sponge has been recorded by 

 Schmidt as having been found in the seas near 

 Denmark and Greenland.* 



66. ISODICTYA TUMULOSA, Bow., in, 344, PI. XCII, figs. 

 17. 



67. ISODICTYA RUGOSA, Boiv., m, 332, PI. XCI, figs. 

 15. 



" On the 23rd June, 1875, I received a specimen of 

 this sponge in a bottle of sea-water in a living con- 

 dition from Mr. Hillier, of Eamsgate. In the living 

 condition the surface is not nearly so rugose as in the 

 drier state, and the sponge abounds in gelatinous 

 sarcode, which it sheds in considerable quantities on 



* ' Grundziige einer Spongien-Fauna des Atlantischen Gebietes/ 

 1870, p. 80. 



