A car. 



Ill 



to lay their eggs upon the ground, under stones, in grass, the crevices Table-case 

 of walls, etc. The Ixodidae are divided into two suh-families. 



Besides the specimens of Ixodidae exhibited in Case 26, a few 

 specimens are on view in the North Hall. 



SuB-FAM. — Argasinac. 



In the Argasinae the jaws are overlapped by a forward expan- 

 sion of the body, and the skin is leathery and coriaceous ; the male 

 and female are very similar in appearance (Genera: Argns and 

 OrnitJiodoros). 



The x\rgasinae are chiefly parasitic on human beings, birds, 

 and bats. The human tick-fever of 

 tropical Africa (Spirillosis) is conveyed 

 by the species known as OrnitJiodoros 

 moahata ; the fowl-tick {^Argas per- 

 sicus) is also known to transmit 

 spirillosis amongst its hosts. 



SuB-FAM. — Ixodinae. 



The mouth-parts of the Ixodinae 

 are terminal. The skin is smooth ; 

 a firm chitinous shield covers the 

 whole of the back of the male, but 

 leaves a considerable portion of that 

 of the female uncovered. 



Several of the members of this 

 family are known to convey infectious Mm-garopus onrntZaizts, the Cattle 

 •' •' . Tick; distended female, x 5. 



diseases ; perhaps the most important (After Salmon and Stiles.) 



of these is the cattle-tick (il/ar^a/'o^j«s 



annulatus), a widely distributed form, which is the carrier of 



Texas-fever (Piroplasmosis). 



Fu 



Sub-order IV.— PEOSTIGMATA. 



Acari with a single pair of tracheal stigmata, which are situated 

 on the anterior part of the body (except in the Halacaridae, in 

 which the tracheae are absent). 



The Acari of this group differ greatly in their habits ; most of 

 them are free-living and are found in moss, under stones, on 

 plants, etc. They chiefly feed upon vegetable substances, but 

 many of them prey on minute animals. There are four families : 

 Tromhidiidae, Hydrachnidae, Halacaridae, and Bdcllidac. 



