320 A MONOGRAPH OP THE 



Since the above description was written, I have received 

 a second specimen from Mr. Norman, who obtained it from 

 Mr. Cooper, of Guernsey, who found it at Vazon Bay. It 

 is smaller than the type specimen, but in external cha- 

 racters it closely resembles it, excepting that the develop- 

 ment of the branches is in a curved plane instead of being 

 in a nearly flat one, and in consequence of having been too 

 much washed it has lost its brown colour, and is now a 

 light gray. 



31. IsoDiOTYA NoRMANi, Bowerbunk. 



Sponge. Sessile, massive, or sub-fistulous. Surface 

 minutely hispid. Oscula large and numerous, slightly 

 elevated, or sub-fistular. Pores inconspicuous. Der- 

 mal membrane pellucid, spiculous; spicula sub-fusi- 

 formi-acuate, long and slender, rarely acerate. Skele- 

 ton. Primary lines rarely more than trispiculous'; 

 secondary lines unispiculous, occasionally bispiculous ; 

 spicula fusiformi-acuate, stout. External defensive 

 spicula same as those of the skeleton. Tension 

 spicula sub-fusiformi acuate, long and slender. Re- 

 tentive spicula bicalcarate, simple, bihamate, and 

 rare]y palmato-equi-anchorate. 



Colour.— Dried, fawn yellow. 



Habitat. — Guernsey, Rev. A. M. Norman. 



Ewamined. — In the dried state. 



My friend the Rev. A. M. Norman, sent me two speci- 

 mens of this sponge. The smallest did not exceed an inch 

 and a half in diameter, and was coating on both its broad 

 surfaces, a small irregular mass of NuUipora polymorpha. 

 This specimen was of a light ochreous yellow, with a tinge 

 of rose colour. It had several slightly elevated oscula, 

 the largest of which did not exceed the eighth of an inch 

 in diameter. The second specimen is two inches and three 

 quarters in length, two inches in width, and one and a half 



