26 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



Fig. 26. Tetractinellid. Hymeraphia ? Globo-stellate in colloidal silica ? a X 275, 

 b X 550 diameters. 



Fig. 27. Tetractinellid. Geodia ? sp. Dermal spicule. X 275 diameters. 



Fig. 29. Tetractinellid. Geodia ? sp. Siliceous globate, spicule ornate. X 275 

 diameters. 



Fig. 30. Tetractinellid. Globo-stellate of dermal layer. In colloidal silica? 

 X 275 diameters. 



Fig. 31. Geodia 1 ? A siliceous globule, body amorphous silica covered with gran- 

 ules of iron peroxide. X 275 diameters. 



Fig. 32. Geodia ? Pyramidal or zone spicule replaced by amorphous silica. X 80 

 diameters. 



Fig. 33. Hexactinellid. Stauractinella ? sp. Quadriate spicule in amorphous sil- 

 ica. X 80 diameters. 



Fig. 34. Hexactinellid. Stauractinella? sp. Replaced by peroxide of iron and 

 amorphous silica. X 80 diameters. 



Fig. 35. Framework of a Hexactinellid? Mesh spicule in colloidal silica. X 275 

 diameters. 



Fig. 36. Monactinellid. Reniera ? sp. Found in outer margin of nodule. Re- 

 placed by amorphous silica. X 80 diameters. 



These drawings were all made with the camera lucida by Mr. J. II. Emerton of 

 Boston. 



