■ ISODICTYA. 125 



still further complicated by the intermixture of the 

 long and slender tension spicula. The same compli- 

 cation of characters exists in the skeleton structures 

 by the abundant presence of the long slender tension 

 spicula on the interstitial membranes ; so that although 

 but one form of spiculum, that of the fusiformi-acerate, 

 stout and slender, prevails in this sponge, the pecu- 

 liarities of their intermixture render this species a 

 specially perplexing one for specific determination." 



24. ISODICTYA DENSA, BoW., II, 292; III, 355, PI. L, 



figs. 5—7. 



25. ISODICTTA G-EEGORII, BoW., II, 301 ; III, PI. L, 



3. 15—17. 



26. IsoDiCTTA PALLIDA, Bow., II, 297; III, PI. L, figs. 

 8—10. 



Habitat. — Jersey. Tide-marks, Westport Bay (N.). 



27. IsoDiOTYA siuvLkms (Johnston), u, 308; iii, PI. LI, 

 figs. 6, 6. 



1861 Saliclona simulans, Bow. List Brit. Marine Invert. 



Fauna (Brit. Assoc), p. 71. 

 1867 Adocia simulans, Gray. Proc. Zool. Soc, p. 522. 



Habitat. — " Aberystwith, Mr. Bolton," purchased 

 by me from Mr. Ingall's collection ; Guernsey ; 

 Strangford Lough, 1869 ; Birterbuy Bay, Connemara, 

 1875 (N.). 



