102 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 14 



DiASTOPORA, Lamouroux and Milne-Edwards. 



A- specimen belonging to an affixed species of this genus was no- 

 ticed on a fragment of Choinstopetalum impar, but its state of pre- 

 servation did not permit the characters to be ascertained. 



Summary of Species. 



Amorphozoa. 



1 . Conis contortuplicata. 



Anthozoa. 



2. Choristopetalum impar. 



3. Cyathophora? elegans. 



Bryozoa. 



4. Siphodictyum gracile. 

 .5. Chisma furcillatum. 

 6. Diastopora . 



EXPLANATION OF PLATES IV. AND V. 



Plate IV. 



Fig. 1. Conis contortuplicata. External appearance, nat. size. 



2. Portion of surface, enlarged, to show the characters of the lacunae and 



pores. 



3. Internal structure, enlarged. 



4. Another section in which the fibrous structure is shown. 



5. Choristopetalum impar. General mode of branching, nat. size. 5*. Portion 



enlarged to give the two sets of openings. 



6. Vertical section, raag. 5 diameters. 6*. Outline from a direct centre to ex- 



hibit the transverse laminae in the tubes, and traces of concentric layers. 



7. The portion immediately above the transverse fracture displays the surface 



of the lower lamina of a concentric layer, mag. 5 diara. 



8. Surface of the upper lamina or counterpart of fig. 7, mag. 5 diam. 



9. The central boss, gives a transversely exposed concentric lower lamina, 



mag. 5 diam. 



10. Transverse section, mag. 5 diam. 



11. Perfect surface, enlarged. 



12. Cyathophora} elegans, nat. size. General appearance. 12*. Portion, mag. 



4 diam. 



13. Nearly vertical section. Fig. 13 to 15 mag. 4 diam. 



14. Portion of a perfectly preserved exterior, figures 12, 12* giving only casts. 

 J.5. Portion of a specimen killed during development. 



