PLATE XXIX. 



FIG. 

 1, 2. PORELLA MINUTA, p. 326. 



3-5. SCHIZOPORELLA AURICULATA, p. 260. 



6. - with spatulate avicularia. 



7. - , var. a (OCHRACEA). 



8. - , var. j3 (CUSPIDATA) . 



9- - , showing the different forms of avi- 



cularium. 



10, 11. MICROPORELLA iMFRESSA, p. 214; var. a. 



12. MICROPORELLA MALUSII, p. 211, var. invested by 

 a smooth calcareous crust '*. 



* This figure is not referred to in the text. 



