PLATE LXXSII. 265 



PLATES XXIII and LXXXII. 



MiCKOCiONA FicTiTiA, Bowerlcmk. 



Vol. ii, p. 124, ' Mon, Brit. SpoBgiadfe.' 



Since tlie figuring of the type-sponge from Guernsey 

 sent to nie by tbe Rev. A. M. Norman, I have acquired 

 a very much more characteristic specimen of the species. 

 It covers externally and internally a single deep valve 

 of an old oyster shell, and the thickness of the sponge 

 at some parts rather exceeds five lines, the dimensions 

 of the shell being 2|- by 2^ inches. The sponge in 

 its dried state is of a deep flesh-red colour. The sur- 

 face of the sponge on both surfaces of the shell is 

 exceedingly irregular and cavernous, some of these 

 deep depressions being the eighth of an inch in 

 diameter, and at the bottom of several of them there is 

 a translucent oscular membrane. The dermal mem- 

 brane exhibits the same pustulous character that is 

 observable in the type-specimen, and the structural 

 mode of the skeleton is much more in accordance with 

 the general characters of the genus to which it belongs. 

 The remainder of the structural and anatomical 

 characters are identical with those of the type-specimen. 



Desmacidon copiosa, Boiverdan/c. 



Plate LXXXII. 



Sponge sessile, coating. Surface rugged and uneven. 

 Oscula simple, dispersed. Pores inconspicuous. Dermis 

 subcrustaceous ; dermal membrane pellucid, profusely 

 spiculous ; furnished with a stout irregular network, 

 rete polyspiculous ; areas abundantly supphed with 

 spicula ; tension spicula ; tricurvate-acerate, small and 

 slender, equi-curvate, rather numerous ; retentive 

 spicula, simple contort and reversed bihamate, very 

 numerous and rarely biumbonate ]}ihamate, large and 



