312 PLATE LXXXIX. 



Fig. 10. — One of the fusiformi-acerate skeleton 

 spicula. X 250 linear. This figure also represents 

 tlie 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 similaeis, Boirerhanl;. 



Fig. 14. — Represents 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, inccjui-anchorate, 

 retentive spicula from the dermal membrane. X 530 

 linear. 



Desmacidon pannosus, Bowcrhaul-. 



Plate LXXXIX. 



Sponge massive, sessile. Surface rough, ragged 

 and open. Oscula and pores unknown. Dermal mem- 

 brane sparingly spiculous ; spicula acuate, rather 

 short and stout, very ^-ariablc in diameter ; same size 

 as those of the skeleton. Skeleton very open; fibre 



