135 



PLATE LIII. 



ISODICTYA EAMUSCULUS, Boiverbank. 



Vol. ii, p. 314, ' Mon. Brit. Spongiadse.' 



Fig. 1. Represents the type-specimen presented to 

 me by Mr. Gosse. Natural size. 



Fig. 2. - - One of the skeleton spicula. X 250 

 linear. 



Fig. 3. A tension spiculum, from the interstitial 

 membranes. X 250 linear. 



ISODICTYA POCILLUM, Bowerbank. 



Vol. ii, p. 305, ' Mon. Brit. Spongiadse.' 



Fig. 4. Represents the type-specimen in the cabinet 

 of the Rev. A. M. Norman. Natural size. 



Fig. 5. - - One of the skeleton spicula. X 250 

 linear. 



Fig. 6. One of the slender, attenuato-acerate, inter- 

 stitial spicula. x 250 linear. 



ISODICTYA CLAVA, Boiverlank. 



Vol. ii, p. 316, ' Mon. Brit. SpongiadaB.' 



Figs. 7, 8, 9. Three specimens of the species from 

 the Moray Frith sent to me by the Rev. Walter Gregor. 

 Natural size. 



Fig. 10. One of the skeleton spicula. X 250 

 linear. 



Fig. 11. A tension spiculum, from the dermal mem- 

 brane. X 250 linear. 



