THE CARBONIFEROUS AGE. 



139 



it is very unlikely that these creatures were in the 

 coal period limited to one country, and that, after 

 that period, they dropped out of existence for long 

 ages, and then reappeared. Still it may have been so. 



THE TWO OLDEST LAND SNAILS. 



Fig. 14. Pupa Vetusta, Dawson. 

 (a) Natural size, (b) Enlarged, (c) Apex, enlarged, (d) Sculpture, magnified. 



Fig. 15. Conulus Prisons, Carpenter. 

 (a) Specimen enlarged, (b) Sculpture, magnified. 



There are cases of geographical limitation quite as 

 curious now. Here again another peculiarity meets 



