82 PLATE XXXII. 



HYMENIACIDON LACTEA, Bowe 



Vol. ii, p. 163, ' Mon. Brit. Spongiadaj.' 



Fig. 9. Represents the type-specimen of the species 

 from the Moray Frith, on a portion of an old Pecten 

 shell. The patches of the sponge are represented by 

 the lighter portions of the figure opposite the letter (a). 

 Natural size. 



Fig. 10. One of the large acerate skeleton spicula. 

 X 250 linear. 



Since the description of the type-specimen in p. 163, 

 vol ii, ' Mon. Brit. Spongiada3,' I have acquired a very 

 much larger and better developed specimen of the 

 species. It covers by far the greater portion of the 

 surface of the type-specimen of Isodictya obscura 

 represented by fig. i, plate Ixxiv, vol. iii, ' Mon. Brit. 

 Spongiadre.' Although developed to so much greater 

 an extent than in the type-specimen, the sponge still 

 exhibits the same thin paper-like structure that cha- 

 racterises the type one, and the milk white colour in the 

 dried state is like that of the small patches of the 

 sponge in the type-specimen. The anatomical struc- 

 tures of the two specimens are also in perfect accord- 

 ance in all their essential characters, and the only 

 difference is that in the larger specimen the interstitial 

 structures are slightly more developed than in the type 

 one, and therefore they exhibit the generic characters 

 of the species in a more satisfactory manner. 



HYMENIACIDON MEMBRANA, BowerbanJc. 



Vol. ii, p. 165, ' Mon. Brit. Spongiadse.' 



Fig. 11. Represents the type-specimen of the 

 species in the cabinet of the Rev. A. M. Norman. The 

 specimen is spread out on, and is adherent to, a piece 

 of paper. Natural size. 



Fig. 12. One of the acerate, skeleton spicula. x 

 250 linear. 



