PLATE XX. 



PAGE. 



Fig. 1. Platyceras tortum 345 



la. A dorsal view. 



I b. A ventral view of same specimen. 



Ic. Dorsal view of another specimen. 



Fig. 2. AvicuLOPiNNA Americana 337 



A specimen flattened by pressure. 



Fig. 3. PtILODICTYA (StICTOPORA) CARBONARIA 328 



'3a. An imperfect specimen. Natural size. 



:ib. A portion of a branch, magnified to show the pores. 



Fig. 4. PtILODICTYA (StICTOPORa) SERRATA • 327 



A portion, natural size, showing the serrated lateral margins. 



Fig. 5. SyNOCLADIA BISERIALIS 326 



5a. A part of the polyzoum, non-poriferous side. Natural size. 

 5b. A small part of same, magnified to show the dimorphous cells. 



Fig. 6. Macrocheilus Klipparti 346 



(ia. A small, short specimen, with the lip broken away. 



66. A large individual, also having the lip broken away, and showing the thickened iuuer 



lip twisted into a prominent told below. 

 6c. Another view of the last. 



Fig. 7. SCHIZODUS CUNEATU.S 336 



View of right valve. Natural size. 



