PLATE VII. 



" HALICHONDRIA CORALLOIDES, Boiverbank. 



Fig. 1. Represents the sponge of the natural size. 



Fig. 2. A small portion of the dermal membrane 

 exhibiting the fasciculated structure of its rete. X 

 80 linear. 



Fig. 3. One of the acerate skeleton spicula. X 

 150 linear." 



" HALICHONDRIA FLABELLIFERA, Bowerlarik. 



Fig. 4. Represents the sponge enveloping nearly 

 the whole of a specimen of Nullipora polymorpha, 

 natural size. 



Fig. 5. A small portion of the dermal membrane 

 showing the more or less fasciculation of its spicula. 

 X 250 linear. 



Fig. 6. One of the subfusiform cylindrical tension 

 spicula of the dermal membrane. X 420 linear. 



Fig. 7. One of the basally and occasionally apically 

 spinous fusiform, acerate external defensive spicula. 

 X 240 linear. 



Fig. 8. A bidentate, equi-anchorate, retentive spi- 

 culum from the dermal membrane. X 420 linear. 



Fig. 9. One of the bidentate, retentive spicula from 

 the dermal membrane. X 420 linear. 



Fig. 10. A fusiforini-acuate skeleton spiculum. X 

 420 linear." 



