PLATE XXIV. 68 



Some of tlie specimens I have from the Diamond 

 Grounds, oii' Hastings, very thinly coat the stones on 

 which they are based, while from the same locality I 

 have one specimen that is five inches in length and 

 three inches at its greatest breadth, and the thickness 

 and surface characters very like the specimens 

 figTired. I have figured a portion of one of the long- 

 slender, skeleton columns of this sponge, not only to 

 illustrate the anatomical structure of the species, but 

 also in strong contr-ast with, the remarkably short 

 skeleton columns of M. atnisarir/uinea, represented by 

 fig. 269, plate xxxiv, vol i, 'Mon. Brit. Spongiadaa.' 



MiCBOOIONA ATBASANtiUiNEA , Boircvhank. 

 Vol. ii, p. 138, ' Mon. Brit. Spongiada;.' 



Fig. 14. — Represents a specimen of M. atrascmc/'mnea 

 from the small cave on the north side of St. Kathe- 

 rine's Island, Tenby. 



Fig. 16. — One of the long, slender, tension spicula, 

 from the dermal membrane. X 150 linear. 



Fig. 16. — A tiicurvate, acerate, tension spiculum, 

 from the dermal membrane. X 250 linear. 



Fig. 17. — One of the skeleton spicula from the 

 skeleton column. X 150 linear. 



Fig. 18. — One of the terminal, skeleton spicula, 

 elongated to act as an external defensive spiculum. 

 X 150 Hnear. 



Fig. 19. — A sub-spinulo-acuate, entirely spined, inter- 

 nal defensive spiculum. X 250 hnear. 



For further illustrations of this species see vol. i, 

 plate xxxiii, fig. 368, for a single skeleton column in a 

 fully developed condition, X 175 linear; and also fig. 

 369, plate xxxiv, in the same volume, for a sectional 

 \4ew of the sponge at right angles to its surface. X 

 1 08 linear. 



I received some thin flakes of this sponge from Mr. 

 Parfitt, of Exeter, on the 1st of March, 1872, who stated 

 that he had scraped it ofi" the shell of one of the 

 recently imported American oysters. 



