198 PLATE IiXXIlI. 



HALICHONDRIA COUCHII, Bower&anJc. 



Fig. 12. Represents the type-specimen from Mr. 

 Jonathan Couch. Natural size. 



Fig. 13. A skeleton spiculum. X 250 linear. 



Fig. 14. One of the minute, slender, acerate, tension 

 spicula from the dermal membrane. X 250 linear. 



Fig. 15. One of the contort, bihamate, retentive 

 spicula from the dermal membrane. X 530 linear. 



MlCEOCIONA SIMPLICIMA. 



Fig. 16. Represents the type-specimen of the 

 species in the cabinet of Rev. A. M. Norman. Natural 

 size. 



Fig. 17. One of the skeleton columns. X 60 

 linear. 



Fig. 18. A skeleton spiculum. X 123 linear. 



Fig. 19. One of the long, flexuous, cylindrical, 

 spicula of the dermal membrane. X 123 linear. 



HALICHONDEIA FOLIATA, Boiverbank. 

 Plate LXXIII. 



Sponge branching, branches thin and leaf-like, ex- 

 panding in the same plane. Surface even, coarsely 

 reticulated, minutely hispid. Oscula simple, dispersed. 

 Pores inconspicuous. Dermal membrane thin, pellucid, 

 spiculous ; tension spicula acuate, long, and very 

 slender, dispersed ; retentive spicula dentato-palmate 

 equi-anchorate, and bidentate equi-anchorate, very 

 minute, rather numerous, dispersed. Skeleton. Rete 

 very large and irregular, multispiculous ; spicula flecto- 

 acuate, large, and stout, but short in their proportions. 

 Internal and external defensive spicula, same as those 

 of the skeleton. Interstitial membranes thin and 

 pellucid, tension and retentive spicula same as those 



