136 



PLATE LIU. 



IsoDiCTYA.DiOHOTOMA, BoiverbanJc. 



Vol, ii, p. 309, 'Mon. Brit. SpongiadcC.' 



Fig. 12. —Represents tlie type-specimen of tlie 

 species brought up by tlie trawl aljout a mile ofi 

 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 PiSTULOSA, Bowerhaiik. 



VoL ii, p. 299, ' Mon. Brit. Spongiadse.' 



Fig. 15. — Represents the type-specimen in the 

 cabinet of the Rev. A. M. Norman. 



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

 lineal'. 



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 exteimal appearance and 

 internal structure. 



