312 PLATE LXXXIX. 



Fig. 10. One of the fusiformi-acerate skeleton 

 spicula. X 250 linear. This .figure also represents 

 the tension spicula of the dermal membrane and the 

 external defensive spicula. 



Figs. 11 and 12. Two of the acuate, entirely spined, 

 internal defensive spicula. X 250 linear. 



Fig. 13.- -A bidentate, equi-anchorate, retentive 

 spiculum from the dermal membrane. X 530 linear. 



DESMACIDON SIMILARIS, ItoiuerbanJc. 



Fig. 14. Eepresents the type-specimen in the 

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



Fig. 15. One of the skeleton spicula. X 250 

 linear. This figure also represents the tension spicula 

 of the dermal membrane. 



Fig. 16. One of the slender, acerate, tricurvate, 

 tension spicula of the dermal membrane. X 250 

 linear. 



Fig. 17. A simple bihamate retentive spiculum from 

 the dermal membrane. X 250 linear. 



Fig. 18. One of the contort, bihamate, retentive 

 spicula from the dermal membrane. X 250 linear. 



Fig. 19. A dentato-palmate, inequi-anchorate, re- 

 tentive spiculum from the dermal membrane. X 530 

 linear. 



Fig. 20. One of the bidentate, inequi-anchorate, 

 retentive spicula from the dermal membrane. X 530 

 linear. 



DESMACIDON PANNOSUS, Bowerbank. 

 Plate LXXXIX. 



Sponge massive, sessile. Surface rough, ragged 

 and open. Osculaand pores unknown. Dermal mem- 

 brane sparingly spiculous ; spicula acuate, rather 

 short and stout, very variable in diameter ; same size 

 as those of the skeleton. Skeleton very open ; fibre 



