PLATE XV. 



" HYMENIACIDON TENEBROSUS, BowerbanJc. 



Fig. l.--The type-specimen from Birterbuy Bay. 

 Natural size. 



Fig. 2.- -The specimen of the species collected by 

 the late Dr. Scouler. 



Fig. 3. One of the ovo-spinulate spicula of the 

 skeleton exhibiting its form and proportions, and of 

 those also of the dermal membrane. X 264 linear. 



Fig. 4. The basal end of a fully developed skeleton 

 spiculum. X 425 linear. 



Fig. 5. --The basal portion of a slender specimen of 

 a spiculum from the dermal membrane. X 425 

 linear." 



" ISODICTYA FUNALIS, BowerbanJc. 



The specimens of this species having been mislaid 

 by my friend (Rev. A. M. Norman) I have been 

 unable to give a figure of the sponge, but this is of 

 little moment, as the whole of the available specific 

 characters are structural and microscopical. 



Fig. 6. Represents a portion of the dermal mem- 

 brane exhibiting its subfasciculated character and its 

 numerous bi- and tridentate, equi-anchorate, retentive 

 spicula in slf/i X 94 linear. 



Fig. 7. One of the palmated, bidentate, equi- 

 anchorate, retentive spicula. X 666 linear. 



Fig. 8. A tridentate, palmated, equi-anchorate, re- 

 tentive spiculum. X 666 linear. 



Fig. 9. One of the minute and slender bihamate, 

 retentive spicula. X 666 linear. 



Fig. 10. A skeleton spiculum basally incipiently 

 spinous. X 308.'" 



" 



