108 PLATE XLIV. 



Many other specimens of this species of less size 

 were obtained from Strangford Lough when the one 

 represented by figure 6 was taken by Mr. Norman. 



For the figure of the spiculum of this species I 

 must refer the reader to Plate L, fig. 18, of the 

 present volume. 



The figure of Isodictya simplex was drawn on the 

 stone and printed through an error of mine, instead 

 of that of Halichondria simplex, and the mistake was not 

 discovered until it was too late to remedy it otherwise 

 than has been done above. 



HALICHONDRIA INCRUSTANS, Johnston. 



Vol. ii, p. 249, ' Mon. Brit. Spongiadse.' 



Fig. 7. Represents a fine specimen of the species 

 dredged on the Diamond Trawling Ground, off 

 Hastings. Natural size. 



Fig. 8. One of the cylindrical mucronate spicula of 

 the dermal fasciculi. X 250 linear. 



There is a considerable variation in the amount of 

 the development of the mucronate character in these 

 spicula ; in some it is scarcely apparent, while in others 

 it is very distinctly produced. 



Fig. 9. - - A large, contort, biharnate, retentive 

 spiculum, from the dermal membrane. X 530 linear. 



Fig. 10. One of the small, simple, bihamate, 

 retentive spicula from the dermal membrane. X 530 

 linear. 



The small, simple, bihamate spiculum is not an 

 undeveloped one of the larger description, but a form 

 separate and distinct from it ; and it appears to be 

 quite as numerous as the larger ones. 



Fig. 11. A bidentate, equi-anchorate spiculum, 

 from the dermal membrane. X 530 linear. 



Fig. 12. An average-sized skeleton spiculum of the 

 normal acuate form. X 250 linear. 



I have never succeeded in finding this sponge on the 



