THE TICKS 



137 



Fig. 76. — Capitulum (rostrum), 

 of an argasid tick: h, hypostome; 

 c, chelicerae; p, palpi; b, basis 

 capituli. 



absent in the Argasidae — is a hard, plate-Hke structure located inmie- 

 diately posterior to the capituhim. In the male it usually covers the 

 entire, or almost the entire, dorsal surface, 

 in n\nnphs it covers the anterior portion; 

 while in the adult female it is much smaller 

 and confined to the anterior portion of the 

 liody. 



3. Dorsum. — This term refers to the 

 whole dorsal surface of the body. 



4. Festoons (Fig. 82) are uniform rect- 

 angular areas into which the posterior mar- 

 gin of the body is divided up. Usually 

 eleven may be more or less distinctly rec- 

 ognized. They are most distinct in unfed 

 specimens, but almost or entirely disap- 

 pear in distended females. They are not 

 present m all forms. 



5. Punctations are circular depressions 

 upon the integument from which fre- 

 quently issue hairs. 



6. Ornamentation refers to enamel-like coloration which may be pres- 

 ent on the scutum, capitulum, or other parts. Ticks upon which this 

 coloration occurs are re- 

 ferred to as ornate. 



7. Venter. — This term 

 refers to the whole ventral 

 surface of the body. 



8. The Spiracles (Figs. 

 78 and 78, a) — also called 

 stigmata, stigmal plates, 

 and peritremes — are two 

 respiratory organs sit- 

 uated ventro-laterally. In 

 the Ixodidse they are sit- 

 uated posterior to the 

 attachment of the fourth 

 pair of legs; in the Arg- 

 asidae they are ))etween 

 the third and fourth pairs. 

 The entire structure may 

 be considered as the 

 stigmal plate or peritreme 

 with an opening known as 

 the spiracle or stigmal aperture. The stigmal plates vary in form and 



Fii;. 77. — Capitulum (head), .•scutum (.shield), and 

 foreleg of Margaropus annulatu.s (from photomicro- 

 graph of mounted specimen, by Hoedt). 



