136 PLATE LIU. 



ISODICTYA DICHOTOMA, Boiverbank. 



Vol. ii, p. 309, ' Mon. Brit. Spongiada?.' 



Fig. 12. Represents the type-specimen of the 



species brought up by the trawl about a mile off 



Hastings. Natural size- 

 Fig. 13. One of the skeleton spicula. X 250 



linear. 



Fig. 14. A tension spiculum, from the interstitial 



membranes. X 250 linear. 



ISODICTYA FISTULOSA, Bowerlank. 



Vol. ii, p. 299, Mon. Brit. Spongiadae.' 



Fig. 15. Represents the type-specimen in the 

 cabinet of the Rev. A. M. Norman. 



Fig. 16. One of the skeleton spicula. X 250 

 linear. 



Fig. 17. A tension spiculum, from the dermal mem- 

 brane. X 250 linear. 



Since fig. 15 was drawn I have found among some 

 unexamined sponges from Shetland, by Mr. Barlee, a 

 specimen of this species one and three quarters of an 

 inch in length, rather less than an inch in breadth, 

 and about half an inch in thickness. It agrees with 

 the type-specimen in both external appearance and 

 internal structure. 



