xxvi FLIES AND SLEEPING SICKNESS 321 



animals it may be worth mention that a fossil biting- 

 fly has been discovered in the Miocene shales of 

 Florissant, Colorado. This fly had a remarkably long 

 and strong proboscis. Professor T. D. A. Cockerell 

 recognised it as a tsetse-fly. 



" The mouth parts are preserved, as also the body, 

 wings, and legs, all agreeing so well with the modern 

 tsetse-fly that the generic separation is impracticable." 



Tacked on to the description of this fossil is the 

 subjoined suggestion by Professor Osborn : 



The former existence of a Tsetse-fly in America is of 

 peculiar interest as having a possible connection with 

 the disappearance of some of 

 the Tertiary mammalia. 



The tsetse fly Glossina pal- 

 /x assumed great importance 

 when it was discovered (1903) 

 to be capable of conveying 



trvpanosomes, the parasites 



which cause sleeping sickness. A Fossil Tsetse Fly. 



In the dry terms Of a medical The thorax is a little distorted; 



text-book this disease is defined th . e 8n . ia11 8 . he11 l ar the right 



. .. . wing is a planorbis. 



as : -An endemic disease ol 



different parts of Equatorial Africa, characterised by a 



gradually increasing lethargy, mental and physical 



degeneration, elevated evening temperature, rapid pulse, 



progressive emaciation, and tremors ; after running an 



acute or chronic course, it almost invariably terminates 



fatally. 



This is a dreadful indictment against any disease, but 

 it is more remarkable than appears from this carefully 

 drawn up statement of claim. Although Sleeping 

 Sickness \vas known to medical writers early in the 

 nineteenth century, the disease did not really attract 

 much attention until it was detected in Uganda in 

 1900 by Dr. J. Howard Cook of the Mission Hospital, 

 Mengo. The disease spread very rapidly along the 

 north shore of the Victoria Nyanza, especially in 



Y 



