PLATE XXIX. 



PIG. 



1, 2. PORELLA MINUTA, p. 326. 



3-5. SCHIZOPORELLA AURICULATA, p. 260. 



6. witli spatulate avicularia. 



7. , var. a (ochracea). 



8. , var. /3 (cuspidata). 



9- , showing the different forms of avi- 



cularium. 



10, 11. Microporella impressAj p. 214; var. a. 



12. Microporella Malusii, p. 211, var. invested by 

 a smooth calcareous crust ^. 



* This iigure is not referred to in the text. 



