224 PLATE LXXVI. 



Fig. 11. An average-sized spiculum from the 

 primary lines of the skeleton. X 250 linear. 



Fig. 12. One of the inequi-cylindrical, incipiently 

 spinous spicula from the secondary lines of the skele- 

 ton. X 250 linear. 



RAPHIODESMA SORDIDA, Bowerbank. 



jig. 13. Represents the type-specimen from Jersey 

 in the cabinet of the Rev. A. M. Norman. Natural 



size. 



Pig. 14. One of the subclavate, fusiformi-acuate, 



tension spicula from the dermal membrane. X 250 

 linear. 



Fig. 15. A long and slender, tricurvate, acerate 



tension spiculum from the dermal membrane. X 250 



linear. 



pig. 16. One of the contort, bihamate, retentive 

 spicula from the dermal membrane. X 530 linear. 



pig. 17 One of the small, dispersed, bidentate, 

 inequi-anchorate retentive spicula. X 530 linear. 



Fig. 18. A large, dentato-palmate, inequi-anchorate, 

 retentive spiculum from one of the rosette-shaped 

 groups of spicula. X 530 linear. 



Fig. 19. One of the skeleton spicula. X 250 

 linear. 



ISODICTYA OBSCURA, Bow&rbaA 

 Plate LXXVI. 



Sponge massive, sessile ; surface even, but slightly 

 rugose or papillate. Oscula simple, dispersed. Pores 

 inconspicuous ; dermal membrane pellucid, aspiculous. 

 Skeleton rather compactly constructed, internally 

 regular ; primary lines rarely consisting of more than 

 three or four spicula ; secondary lines unispiculate ; 

 short and stout. 



