Injurious to Man. 33 



quences I afterwards tested the insect [the mite], and 



found it to be the real agent. The experiment was repeated at 

 my suggestion by a medical friend — Dr. R. J. Drummond — who 

 can testify to the result. He described the sensation as somewhat 

 like that produced by the strongest menthol. We both noticed 

 that it had a numbing effect upon the mucous membrane of the 

 mouth. It is evident that this property must be a very efficient 

 protection to the insect. The rapidity with which the secretion 

 acts would cause it to be very quickly ejected if picked up by 

 either a bird or a lizard — the only enemies that would be likely to 

 attack it." Possibly the red colour of these mites is a case of 

 warning coloration. 



Super-Family— IXODOIDEA. 



Key to the Genera of Ticks (Ixodoidea). 



No dorsal shield. Capitulum ventral 



in adults ... ... ... ... Family Argasidae... 2 



Dorsal shield present. Capitulum 



terminal ... ... ... ... Family Ixodidae ... '-\ 



Body flattened, and with a distinct 

 narrow border or margin, com- 

 posed of striations or cells. Eyes 

 never present ... ... ... Argas. 



Body, stout when distended, its 

 margins thick and without any 

 distinct border. Eyes sometimes 

 present ... .. ... ... Ornithodoros. 



Capitulum usually long ... ... ... ... ... i 



Capitulum short ... ... ... ... ... ... 6 



Eyes absent. Anal groove curved 



so as to surround anus anteriorly, 



but open posteriorly ... ... Ixodes. 



Eyes usually distinct. Anal groove 



curved so as to surround anus 



posteriorly, but open anteriorly ... ... ... ...5 



£ Anal plates absent ... ... ... Amblyomma. 



( Anal plates present in male ... Ilyalomma. 



D 



2 \ 



4 { 



