183 A MONOGRAPH OF THE 



I could find very few oscula by the aid of an inch lens ; 

 they were simple orifices, and were scattered on the broad 

 sides of the sponge. In the live state it is probable that 

 they would be more conspicuous. The pores are very few 

 in number, and were rarely to be seen, even with a power of 

 250 linear. This may probably arise from the large quantity 

 of dried sarcode with which the membranes are obscured. 

 The dermal membrane is abundantly furnished with spicula, 

 which frequently assume a flat fascicular arrangement near 

 the margins of the oscula. At other parts of it they are dis- 

 tributed without order, as in the interstitial membranes. 



Montagu has not figured this species, but I have no doubt 

 that the specimen I have described above is the one to which 

 he alludes in his description in ' The Memoirs of the Werne- 

 rian Society,' vol. ii, p. 86. The specimen is now in the pos- 

 session of Dr. Grant, with the original label attached to it. 



There is a specimen in the British Museum, labelled by 

 Dr. Johnston Halichondria aurea, but it does not belong to 

 the same genus as the sponge described above. It is 

 Isodectya permollis of this work. 



I dredged up two specimens of this species at Tenby, both 

 of them coating oyster shells, but neither of them rising from 

 the base, as in Montagu's specimen. In colour, both in the 

 living and dead states, they agree completely with Montagu's 

 type specimen, and in all the anatomical details they cannot 

 be distinguished from each other. With these important cha- 

 racters in unison, the difierence in form is scarcely worthy of a 

 consideration. I subsequently received two small specimens 

 of this species from the Rev. A. M. Norman, who found them 

 in Bantry Bay in 1859. In these specimens there were a 

 number of vesicular bodies, which had every appearance of 

 being the gemmules. They were ^^th of an inch in diameter 

 when fully developed. The membranous coat of the gem- 

 mules was aspiculous. They were filled with minute vesicular 

 molecules. 



