Plate 27 



Figs. 1-6. Petraliella echinata, new species (p. 265). 



1. Zoarium, X 10, incrusting a Nullipore, with ovicell and ancestrula 



and showing the arrangement of the spines. 



2. Same specimen, X20. The oral spines are broken away and the 



aperture is visible. 



3. Another part of Figure 1, X20, with avicularian umbo much de- 



veloped. 

 4, 4'. Two portions of another specimen, X20, with ovicell, avicularian 

 umbo and frontal spines. 



5. Zooecia, X 10. 



6. Microstructure of the frontal, X85. 



D. 5141. Jolo Light, Jolo. 

 7-12. Petraliella tubulifera, new species (p. 264). 



7. Incrusting specimen, X10. 



8. The same specimen, X20, exhibiting young zooecia without avicu- 



larian umbo. The lyrule and cardelles at the proximal border of 

 the aperture are visible. 

 D. 5137. Jolo Light, Jolo. 



9. Unilamellar specimen, X20, in which the avicularian umbo is very 



salient. 



D. 5162. Tinagta Island. 



10. Zooecia, of well-preserved unilamellar zoarium, X20. All of the 



frontal ornamentation is well developed. 

 D. 5574. Simaluc Island. 



11. Zooecia, X20, in which the avicularian umbo is in process of forma- 



tion. 



12. Unilamellar zoarium, >'20, with ancestrular zooecia. 



D. 5179. Romblon Point, Romblon. 

 i 591 1 



