62 PLATE XXIV. 



sent to me by Mrs. Griffiths in MS. long before I was 

 acquainted with the specimens of Microciona carnosa, 

 vol, ii, p. 183, Mon. Brit. Spongiadre, which I subse- 

 quently found at Seunen Cove, and it was not until I 

 re-examined the British species of Hymeniacidon for 

 figuring in the present volume that I detected the 

 error I had fallen into in my early description of the 

 specimens sent to me by Mrs. Griffiths ; and as Mon- 

 tagu's, specific name of plumosa has precedence of that 

 of carnosa, the species must hereafter be designated 

 Microciona plumosa ; the description of the sponge 

 under the designation of M. carnosa being received as 

 that of M. plumosa. 



The general aspect of the species is so different in 

 its living state to what it is in its dried condition, that 

 when I found it alive at Sennen Cove I am not sur- 

 prised that I did not recognise it as the same as the 

 dried sponges sent to me by Mrs. Griffiths, and I 

 accordingly described it at that time without reference 

 to those specimens. 



Fig. 7. A specimen of M. plumosa from Guernsey by 

 the Rev. A. M. Norman. Natural size. From the 

 dried specimen. 



Fig. 8. --The type-specimen from Sennen Cove, 

 Land's End, Cornwall. Natural size, in the dried 

 state. 



Fig. 9. A fusifornii-acerate spiculum, from the 

 dermal membrane. X 250 linear. 



Fig. 10. One of the sub-attenuato-acuate, skeleton 

 spicula, entirely spined. X 250 linear. 



Fig. 11. One of the internal, defensive, attenuato- 

 acuate, entirely spined spicula. X 250 linear. 



Fig. 12. One of the bidentate angulated equi-an- 

 chorate, retentive spicula, from the interstitial mem- 

 branes. X 1250 linear. 



Fig. 13. Represents a small portion of one of the 

 long, slender, and flexuous columns of the skeleton of 

 M. plumosa. X 150 linear. 



This species presents a great variety in its aspect. 



