PLATE XXVIII. 



HYMEDESMIA RADIATA, Bowerbank. 



Vol. ii, p. 149, ' Hon. Brit. Spongiadse.' 



Fig. 1. A magnified view of a small portion of a 

 sponge exhibiting the radiating groups of skeleton 

 spicula in situ. X 80 linear. 



Fig. 2. The basal portion of one of the long and 

 slender attenuato-acerate, skeleton spicula. X 128 

 linear. 



Fig. 3. One of the largest of the clavated attenuato- 

 acerate, incipiently-spined, internal, defensive spicula. 

 X 150 linear. 



Fig. 4. One of the smallest of the same description 

 of spicula as that represented by fig. 3. X 150 

 linear. 



For a representation of the sponge of its natural 

 size, see Plate XVIII, fig. 8, of the present work. 



This specimen exhibits the largest encrusted surface 

 of this tribe of sponges that I have yet seen. The 

 specimen was obtained among the deep sea dreclgings 

 at Shetland by my friend Mr. C. W. Peach in 1865. 



HYMEDESMIA STELLATA, Bowerbank. 



Vol. ii, p. 150, ' Mon. Brit. Spongiadse.' 



Fig. 5. A portion of the type-specimen of H. 

 stellata in the cabinet of the Rev. A. M. Norman, 

 exhibiting ths dermal membrane crowded with its 

 minute cylindro-stellate spicula. X 123 linear. 



Fig. 6. A group of three of the cylindro-stellate 

 spicula. X 530 linear. 



