19? 



PLATE LXXIII. 



HALICHONDRIA FOLIATA, Bower dank. 



Fig. 1. Represents the finest and best-developed 

 specimen from Shetland in the condition in which it 

 came from the sea. Natural size. 



Fig. 2. Is from a small, but well-developed speci- 

 men from Scarborough in the dried state. Natural 

 size. 



Fig. 3. One of the slender, acuate, tension spicula 

 from the dermal membrane. X 250 linear. 



Fig. 4. A skeleton spiculum. X 250 linear. 



Fig. 5. One of the tricurvate-acerate, tension 

 spicula from the interstitial membranes. X 250 

 linear. 



HALICHONDRIA EDUSA, Bowerbarik. 



Fig. 6. Represents the type-specimen of the species 

 in the wet condition. In the cabinet of the Rev. A. 

 M. Norman. Natural size. 



Fig. 7. A small portion of the dense polyspiculous, 

 dermal reticulation. X 180 linear. 



Fig. 8. An acerate skeleton spiculum. X 250 

 linear. 



Fig. 9. A tension spiculum from the interstitial 

 membranes. X 250 linear. 



HALICHONDRIA REGULARIS, Bowerbank. 



Fig. 10. Represents the type-specimen from Sark. 

 Natural size. 



Fig. 11. One of the skeleton spicula. X 250 

 linear. 



