82 



Margaropus annulatus Say. 



The shield is plainly longer than broad, with a distinct eye-spot at 

 each lateral corner, and behind the eye the shield is suddenly nar- 

 rowed; the coxae of the female are without spines, but the male has 

 2 on coxae I. This is the common cattle tick of the United States, and 

 disseminates the Texas fever. Mr. Hunter has taken it once from a 

 rat in a barn at Dallas, Tex. 

 Rhipicephalus sanguineus Latreille. 



The shield of the female is oval, and longer than broad, with an 

 eye-spot at each outer corner. Coxa I with 2 teeth; a smaller tooth 

 on each of the other coxae. Stigmal plate long, comma shaped. In 

 the male there is a corneous plate each side of the anus, and on middle 

 of posterior margin a projection, or short tail. 



This species is common in tropical countries, and Nuttall has 

 recorded specimens from the black rat in India. 

 Hyalomma aegypticum Linne. 



The shield of the female is as broad as long, and the eye-spot is 

 slightly above each outer corner. Coxa I has 2 large teeth, and a 

 small tooth on each of the other coxae. In the male there are 2 corne- 

 ous plates each side of anus, and behind is a pair of small tubercles. 



This is a common tick in the warmer parts of the Old World; and 

 Nuttall has recorded young specimens on the black rat. 



GAMASID^:. 



The Gamasid mites, although much smaller than the ticks, are 

 large enough to be seen by the naked eye. They are active, and 

 most are not parasitic, at least for part of their time. The palpi are 

 simple, of 5 joints; the mandibles are elongate, retractile, and usually 

 chelate at tip. There are no eyes. The dorsum and often the venter 

 shows one or more corneous shields or plates, frequently a number of 

 them; one or two on the dorsum, and on the venter one between the 

 coxae, called the sternal plate; one behind this, the genital plate; one 

 behind the latter, the ventral plate; and one surrounding the anus, 

 the anal plate. Frequently some of these are absent or united to one 

 of the others. 



The legs are slender, usually of 6 joints, with a long tarsus that 

 terminates in 2 claws, and often a sucker, or caroncle. The stigmata, 

 or spiracles, are lateral above and between coxae II and IV, and 

 usually provided with a slender peritreme reaching forward toward 

 the head. Nearly all the Gamasidae deposit eggs, and the young 

 often differ considerably from the adult in structure. There are 

 two, and perhaps sometimes three, nymphal stages. In one of these 

 nymphal stages the mite is apt to attach itself to an insect for the 

 purpose of being carried to a similar locality, where it may feed and 

 mature. The coprophagous and xylophagous insects are especially 

 concerned in the diffusion of these mites. 



