PLATE V. 



" HALICHONDRIA VIRGEA, Bowerbank. 



Figs. 1 and 2. Represent the largest of the four 

 specimens of the species sent to me by Mr. Norman. 

 Natural size. 



Fig. 3. A small portion of the dermal membrane, 

 exhibiting the mode of'the fasciculation of the spicula. 

 X 264 linear. 



Fig. 4. One of the subfusiform, basally spinous, 

 acuate, skeleton spicula. X 264 linear. 



Fig. 5. A long and slender, acuate, tension spicu- 

 lum from the dermal membrane. X 264 linear. 



Fig. 6. A large bidentate, equi-anchorate, reten- 

 tive spiculum from the dermal membrane. X 400 

 linear. 



Fig. 7. One of the small and numerous bidentate, 

 equi-anchorate, retentive spicula. X 400 linear." 



" HALICHONDRIA ROBERTSONI, Bowerbank. 



Fig. 8. Represents the sponge in the dried state. 

 Natural size. 



Fig. 9. A small portion of the dermal membrane, 

 exhibiting the broad, flat, irregularly dispersed fasciculi 

 of the dermis. X 94 linear. 



Fig. 10. A fully-developed, hastate, cylindrical 

 spiculum from the dermal membrane. X 264 linear. 



Fig. 11. One of the largest of the tridentate, equi- 

 anchorate, retentive spicula from the dermal mem- 

 brane. X 400 linear. 



Fig. 12. One of the smallest tridentate, equi- 

 anchorate, retentive spicula from the dermal mem- 

 brane. X 400 linear. 



Fig. 13. One of the minute and slender, bihamate, 

 retentive spicula from the dermal membrane. X 400 

 linear. 



Fig. 14. One of the short and stout, basally and 

 apically spined, acuate skeleton spicula. X 308 

 linear.' 



