Fig. 



7. Internal surface of shell of Waldheimia {Ter.) mistralis, showing the imbricated arrange 



ment of the extremities of the prisms, which are seen longitudinally at a. — 

 Magnified 100 dimeaters. 



8. External surface of shell of Waldheimia {Ter.) australis, showing the large trumpet- 



shaped ends of the vertical passages, covered-in by the opercular disks, which 

 have radiating lines proceeding from them. Magnified 100 diameters. 



9. Calcified membrane of the shell of Waldheimia {Ter.) australis, having attached to it 



some of the caecal tubuli, crowded with cells. Magnified 150 diameters. 



10. Portion of the surface of the calcareous loop of Waldheimia {Ter.) amtralis, showing the 



imbricated arrangement of the extremities of the flattened prisms, and the 

 absence of perforations, — Magnified 1 00 diameters. 



11. Portion of the internal surface of the shell of Terebratulina caput-serpetitis, showing 



the imbricated arrangement, and the internal orifices of the vertical perforations, 

 arranged in rows. — Magnified 100 diameters. 



12. Portion of the external surface of the shell of Terebratulina caput-serpentis, showing 



the external orifices of the perforations, opening somewhat obliquely upon the 

 ridges of the plications. — Magnified 100 diameters. 



13. Portion of the shell of Terebratulina caput-serpentis, partially decalcified by macera- 



tion in acid, showing the csecal tubuli, in situ. — Magnified 100 diameters. 



14. Portion of the internal surface of the shell of Megerlia truncata, showing the usual 



imbricated arrangement and the internal orifices of the vertical perforations, 

 with two of the peculiar elevations or ' bosses,' on which no passages open. — 

 Magnified 100 diameters. [N.B. By an oversight on the part of the artist, the 

 surface of these bosses is not represented as partaking of the general imbricated 

 character of that of the rest of the shell, which is really the case.] 



