l62 



ZOOLOGY 



Geography 

 of ancient 

 times 



Photograph from Am. Mus. Natural History 



FIG. 34. Tipula maclurei, a crane-fly fossil in the Miocene shales of Florissant, 

 showing the details of the markings of body and wings, as they appeared in life. 

 Enlarged. 



ance. Among suggested causes, disease often appears 

 probable, and if insects existed which would be likely 

 to carry the parasites of epidemic diseases, the probabil- 

 ity is increased. It was therefore very interesting to 

 discover, several years ago, a fossil tsetse fly in the Floris- 

 sant shales. Since then others have been found, so that 

 today we know four species of fossil Glossina from this 

 locality. They may have been the cause of the extinc- 

 tion of some of the Miocene animals, but why did they 

 themselves finally disappear, remaining only to plague 

 the men and beasts of Africa ? To this question we 

 have as yet no answer. 



6. The Florissant fossils may throw light on events 

 happening in very different parts of the world. During 

 Tertiary time there was a long period when the present 

 Isthmus of Panama was under water. We know this 

 from the marine fossils found in cutting the canal, and 



