EXPLANATIO^^ OF PLATE LXI. 



Maccoyella COEBIEKSI!?, Moore, *^>. (/). 



Fig. 1. Articulus of the left valve. 



„ 2. Portion of a left valve with posterior auricle. 



„ 3. Left valve, one of the largest specimens, with costsp. 



„ 4. A similar left valve. 



„ 5. A mucli broader example of a left valve, with posterior alation 



approaching Oxi/loma rockicoodeiisis, Etli. fil., in outline. 



„ (i. Longitudinally elongated individual witli well preserved sculpture. 



ArCELLA HUGHENDENENSIS, Et/ieridffe. 



,, 7. Portion of the united valves. The auricle of the right valve and the 



anterior dorsal margin of the latter are seen to be crenidated - 



X 2. 

 „ 8. Left valve of a typical specimen. 

 „ 9. G-roup of young individuals on the weathered surface of a piece of 



impure limestone. 

 ,. 10. The valves in apposition showing the auricle of tlie right valve 



received in an anterior inflection of the cardinal margin — X 2. 

 „ 11. Portion of valves in apposition but exhibiting the area of tlie left 



valve— X 3. 

 ,, 12. The specimen of which Fig. 11 is a partial enlargement — X 2. 



AnISOMTON (?) HEPHES.SU8, Eth. Jil. 



„ 13. Lateral view. 

 ., 11. Apical view. 



