PLATE XXXIV. 



Fig. 8. One of the sub-fusiformi-acuate skeleton 

 spicula. X 150 linear. 



Fig. 9. One of the slender flexuous tension spicula 

 of the dermal membrane. X 150 linear. These spicula 

 assume every imaginable form of flexuousness. 



I am indebted to Professor Dickie, of Aberdeen, for 

 six specimens of this sponge from Lough Larne. They 

 agree in all their structural peculiarities with the speci- 

 mens previously described. 



HYMENIACIDON PACHYDERMA, Bowerbank. 



Vol. ii, p. 184-, ' Mon. Brit. Spongiadae.' 



Fig. 10. Represents the type-specimen of the 

 sponge presented to me by Mrs. Griffiths. Natural 

 size. 



Fig. 11. One of the skeleton spicula of the sponge. 

 X 150 linear. 



HYMENIACIDON ARMATURA, Bower dank. 



Vol. ii, p. 183, ' Mon. Brit. Spongiadse.' 



Fig. 12. Represents the type-specimen from Strang- 

 ford Lough. Natural size. 



Fig. 13. One of the acuate skeleton spicula. 

 X 250 linear. 



Fig. 14 One of the cylindrical spicula from the 

 dermal membrane. X 250 linear. 



Fig. 15. One of the attenuato-acuate, entirely - 

 spined, internal, defensive spicula. X 530 linear. 



