ISODICTYA. 129 



was a large gibbous valve of Pecten moximus, covered 

 within and without with a thin coat of Raphyrus 

 Griffithsii, upon which on the inner surface of the 

 shell were several parasitical marine animals, and 

 among them two specimens of Isodictya ferula, par- 

 tially immersed in a thin spreading specimen of 

 Isodictya simulo, agreeing both in external form and 

 in anatomical structure with the type-specimen of that 

 species. This is the second specimen of that sponge 

 that I have seen." 



Dr. Bowerbank having named one species of this 

 genus I. simulans, and another I. simulo, it became 

 necessary to rename the latter. 



32. ISODICTYA FILAMENTA, Bow., in, 286, PI. LXXXV, 



figs. 1 4. 



33. ISODICTYA PAUPERCULA, Bow. 9 n. sp., iv, PI. X, 



figs. 68. 



" Sponge coating, thin. Surface minutely rugose. 

 Oscula simple, dispersed. Pores inconspicuous. 

 Dermal membrane pellucid, sparingly spiculous ; 

 spicula acerate, very slender, dispersed, few in number. 

 Skeleton rete slender and fragile ; primary lines 

 mostly unispiculous, occasionally bi- or rarely trispicu- 

 lous ; secondary lines unispiculous ; spicula acerate, 

 rather stout and long. 



" Colour. In the dried state, dull dark green. 



"Habitat. Birterbuy Bay, Ireland, in 10 fathoms; 

 Rev. A. M. Norman. 



" Examined. In the dried state. 



" This sponge covers nearly the whole of the inner 



VOL. iv. 9 



