ISODICTYA. 123 



21. ISODIOTTA FISTULOSA, SoW., II, 299; III, 136, PI. 



LIII, figs. 15—17. 



Habitat. — ^A small sponge named by Bowerbank as 

 belonging to this species is referred to in his note on 

 Isodictya MacAndrewi. It was procured by me in 1876 

 in Birterbuy Bay (N.). 



22. IsoDiOTYA DiOHOTOMA, Bow., II, 309 ; HI, PI, LIII, 

 figs. 12—14. 



23. ISODIOTTA PERPLEXA, BoW., VL. Sp., IV, PI. IX, figS. 



4—6. 



" Sponge massive, parasitical. Surface smooth and 

 even. Oscula simple, dispersed. Pores incon- 

 spicuous. Dermal membrane reticulate ; rete irregular, 

 rarely exceeding trispiculous, spicula variable in size, 

 fusiformi-acerate, mostly large, same size as those of 

 the skeleton ; tension spicula acerate, long and slender, 

 numerous, dispersed. Skeleton with primary lines bi- 

 or trispiculous, irregularly disposed; secondary lines 

 mostly unispiculous, abundant and very irregularly 

 disposed; spicula fusiformi-acerate, large and long. 

 Interstitial membranes abundantly spiculous ; tension 

 spicula acerate, long and slender, same as those of the 

 dermis. 



" Colour. — In the dried state, dark brown with a tint 

 of purple. 



" Habitat. — Westport Bay, Ireland, in 6 — 6 fathoms ; 

 Eev. A. M. Norman. 



"Examined. — In the dried state. 



