23, 24. Coccoiieis — two species. 



25. Cocconema. 



26. Campy lodiscus. 



27. Rosalina globularis, — probably tbe Rotalia stigma Ehr. 



Viewed as a transparent object, and hence representing 

 a section of the animal. 



28. The same species in an advanced stage of growth — 



transparent. 



29. The decalcified animal of the same. 



30. Polystomella — transparent. 



31. 32. Peneroplis — transparent. 



33. Textillaria — transparent. 



34. A Foraminifer : genus uncertain — transparent. 



35. Inferior surface of Truncatulina tuberculata, as an opaque 



object. 



36. 37. Spiroloculiua — transparent. 

 38. « Biloculina : front view — opaque. 



38. & lateral view — transparent. 



39. Lagena (Lagenula auctorum) transparent. 



40, 41. Spicnla of Sponge— probably of Tetheia. This and 



all the subsequent forms are represented as opaque 

 objects. 



42. Globular cortical balls of Geodia. 



43. Radiating spiculum of the same. 



44. Spiculum of some unknown sponge- 



45. Calcareous spiculum. 



