71 



PLATE XXVIII. 



Hymedesmia RAHiATA, Buwerban/c. 



Vol. ii, p. 149, ' Mcjii. Brit. Sjioiigiadse.' 



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

 sponge exhibiting tlie radiating groups of skeleton 

 spicula in sitiL X 80 linear. 



Fig. 2. — The basal portion of one of tlie 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 XA^III, 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 dredgings 

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



Hyjiedesmia stellata, Boirerhnnk. 



Vol. ii, p. 150, ' Mon. Brit. Spongiacl^^.' 



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

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

 exhibiting the dermal membrane crowded with its 

 minute cylindro-steUate spicula. X 123 linear. 



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

 spicula. X 530 hnear. 



