PLATE 15. 



Fig. 10. — Membranipora patuJa Hincks. A few zocecia showing the 

 broad aperture (ap.), spines (sp.), the triangular avicularia (av.) and the 

 small oceeia (oe.). X 30. 



Fig. 11. — Membranipora sanclalia Robertson. A young zooeeium in which 

 the aperture (ap.) occupies the whole of the front. X 30. 



Fig. 12. — M. sandalia. A young zoceciuni in which the aperture is re- 

 duced in size and is outlined by a circular oral rib (o. rb.). X 30. 



Fig. 13. — M. sandalia. A few zooecia in an intermediate stage of growth 

 showing the calcareous ribs (rb.) extending from the lateral margins, and 

 the area (ar.) below the orifice where later an avicularium is situated. X 30. 



Fig. 14. — M. sandalia. A few zooecia in the adult stage showing the 

 sessile avicularium (av.) below the orifice and the calcareous lamina (cal. 

 lam.) almost or entirely obscuring the calcareous ribs visible at the stage 

 represented in fig. 13. X 30. 



Fig. 15. — Membranipora spinifera Johnston. A few zocecia showing the 

 granular margin beset with spines, and the pedunculated avicularium (or.). 

 X 30. 



Fig. 16. — Membranipora telvuelcha d'Orbigny. A few immature zocecia 

 and a portion of the growing rim (gr. r.). X 30. 



Fig. 17. — M. tehnelclia. An immature zooeeium showing the beginning of 

 the calcified spines at the distal angles (arig.). X 30. 



[826] 



