ISODIOTYA. 141 



the arrangement of the skeleton tissues much more 

 regular than in those of the type-specimen, while in 

 others the same confusion of the structures prevailed. 

 In all the anatomical characters these specimens were 

 in perfect accordance with those of the type-sponge, 

 excepting that there was a slight difference in the size 

 of the spicula. The spicula of the younger parts of 

 Mr. Norman's specimens were -of the same size as 

 those of the type-specimen, but in the old and more 

 mature parts they were rather longer and stouter than 

 those of the type-sponge in the Liverpool Museum." 



55. ISODICTYA IMITATA, JBow., in, 226, PL LXXVI, 

 figs. 3 6. 



56. ISODICTYA NODOSA, Bow., n. sp., iv, PI. XII, 

 figs. 67. 



" Sponge massive, sessile, more or less nodose, para- 

 sitical. Surface minutely rugose. Oscula simple, 

 large, frequently terminating in nodous elevations. 

 Pores conspicuous, dispersed. Dermal membrane 

 pellucid, sparingly spiculous ; tension spicula sub- 

 fusiformi-acuate, same as those of the skeleton. 

 Skeleton multispiculous, rather irregular, secondary 

 lines irregular, varying from unispiculous to bi- or tri- 

 spiculous ; spicula subfusiformi-acuate, minute, vari- 

 able in diameter. Interstitial membranes aspiculous. 

 Colour. In the dried state, light brown. 

 Habitat. Birterbuy Bay, Ireland. Rev. A. M. 

 Norman. 



" Examined. In the dried state. 



cc 



It 



