135 



PLATE LIII. 



IsoDiCTYA EAMUSCULTJS, Bovjerbank. 



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



Fig. 1. — Represents ttie type-specimen presented to 

 me by Mr. Gosse. Natural size. 



Fig. 2. — One of tlie skeleton spicula. X 250 

 linear. 



Fig. 3. — A tension spiculum, from the interstitial 

 membranes. X 250 linear. 



IsoDiCTYA POCiLLUM, Boiverbcmk. 



Yol. ii, p. 305, ' Mon. Brit, Spongiadee.' 



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

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



Fig. 6. ■ — One of the skeleton sjoicula. X 250 

 linear. 



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

 stitial spicula. X 250 hnear. 



IsoDiCTTA CLAVA, Boiuerbcm/c. 



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



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

 the Moray Frith sent to me by the Rev. Walter Gi'egor. 

 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. 



