568 



MEDICAL ENTOMOLOGY 



NEUMANN'S TABLE OF THE FAMILIES OF THE ACARINA. 



Non-vermi- 

 form 

 Acarina. 



Legs inserted /Legs with 5 articles .... 

 directly into / with (provided with 



theintegu- trachea booklets 



ment. without Legs with I rhelirerae I didactylous or 

 epimera. I 6 articles. ] C ' era6 ' 1 styliform . 

 With no tracheae (marine 

 \ Acarina) .... 



Legs articula- 

 ted on distinct 

 epimera. 



Natatorial legs (aquatic Acarina) 



Oribatidae. 



Ixodidee. 



Qamasidaa. 



Halacarida-, 

 Hydrachnida. 



/Chelicerae styliform ; palps 



free, antenniform . . Bdellida?. 



Ambula- 

 tory Legs. 



Cheliceras styliform or in 

 claws ; palps free ; pre- 

 daceous .... 



Vermiform Acarina 



Chelicerse didactylous ; palps 

 cylindrical or conical, and 

 partially adherent to the 

 lips ..... 



.Legs with 5 articles .... 



v Legs with 3 articles . . , 



Trombidiida-. 



Sarcoptidze. 

 Eriophyidae. 



Demodicidas. 



FAMILY IXODIDAE 



Acarina with the abdomen compressed dorso-ventrally, unsegmented 

 and completely fused with the cephalothorax ; a pair of spiracles is sit- 

 uated in the posterior part of the body behind the last pair of legs. The 

 capitulum articulates with the anterior end of the body and bears the 

 rostrum or beak, which consists of the jointed palps (pedipalps), hooked 

 mandibles lying in sheaths, and the fused maxillae forming the hypostome, 

 which is armed with rows of recurved teeth simulating a rasp. The anus 

 is situated ventrally in the posterior third of the body, and the sexual 

 orifice in the anterior third. There are four pairs of legs, each consisting 

 six joints or segments, terminating at their extremities in two curved claws 

 and a ventral pad or pulvillum ; the first pair contains a small fossette 

 at its extremity known as ' Hatter's organ ', which is probably of a sensory 

 nature. 



Of all the Acarina, the giant mites or ticks are the most familiar, and 



in tropical countries are to be found on almost every mammal. As is 



well known they are the transmitters of several species 



Ticks in relation to o f t h e Piroplasmata and Spirochaetae, and the diseases 



Parasites which result from the invasion of the blood by these 



parasites are some of the most deadly which affect 



the domesticated animals. In, 1893 Smith and Kilbourne proved by 



