12 Zoology of Colorado 



have been set aside or even lost without falling into the hands of 

 someone competent to describe them. It cannot be too strongly 

 urged that materials of this kind are not to be regarded as mere 

 private property, but should be placed where they will be studied, 

 and saved for the use of posterity. In such localities as Florissant 

 many of the specimens are unique, and will probably remain as 

 the only evidence of the existence, ages ago, of the species they 

 represent. The described species of insects from the Florissant 

 shales number considerably over a thousand, while others have 

 been collected and await description. Among the most interest- 

 ing are four species of tsetse-flies (Glossina), which sucked the 

 blood of Miocene mammals. In Africa, the nagana disease 

 so fatal to cattle is due to a parasitic Protozoan (Trypanosoma) 

 which is carried by a kind of tsetse-fly, Glossina morsitans. 

 Sleeping sickness of man, which has wiped out whole com- 

 munities in central Africa, is produced by another Proto- 

 zoan, carried by Glossina palpalis. It is of course impossible 

 to detect fossil Trypanosomes in the fossil tsetse-flies, but it 

 may well be that they harbored them, and this may account 

 for the mysterious extinction of some of the Tertiary mammals. 

 The objection has been made, that in Africa the native mammals 

 (antelopes, etc.) do not succumb to the nagana disease, but have 

 actually acquired a tolerance of the Trypanosomes, so that they 

 serve as reservoirs for the dangerous parasites, the flies carrying 

 them from the wild animals to the domesticated stock. Therefore, 

 it was argued, it ought to be expected that in Miocene times the 

 tsetse-flies, even if carrying Trypanosomes, would not injuriously 

 affect the wild animals. However, this does not take into account 

 the Miocene migration, whereby the flies may have entered the 

 country from Asia, and rapidly spread over it, causing disease in 

 the native animals, which had never acquired immunity or toler- 

 ance. The living tsetse-flies are confined to Africa (with 17 

 species), except that one occurs in southern Arabia. Thus they 

 were totally unexpected at Florissant, and when the first one, 

 unfortunately headless, fell into the hands of Scudder, he described 

 it as a member of the CEstridae, the family of bot-flies and warble- 

 flies. In 1907 Mr. Geo. N. Rohwer found a good specimen, show- 

 ing the proboscis, and there was little difficulty in determining its 

 true nature. Such a surprising discovery was naturally met with 



