88 



PROCEEDINGS OF THE NA TIONAL MUSEUM. 



VOL. XXVIII. 



Fk;. Ills.— Caruncle 



rTERiiLIfHrs. 



Fig. Itli).— Leg cif .\nal- 



GES; o, OLECRANON PRO- 

 CESS; p. TARSAL PROCESS. 



is ji hiickward projection from .some of the basal joints of le^- 1; these 

 are the olecranon processes. On the dorsum are stitf bristles, the 

 size and ai'rangement of which ati'ord good .spe- 

 cific characters. The vulva is situated between 

 the l)ases of the third and fourth pairs of coxa^; 

 it is usually marked by a curved line, which is 

 termed the lyra. In the male there is a smaller 

 U-shaped mark. The copulatory opening of the 

 female is, however, a small aperture behind the 

 anus. The anal aperture is a simple slit at the tip 

 of the body. Each side of it in the male there 

 is a circular mark or sucking disk; these are the 

 mating or copulatory suckers. The tip of the 

 abdomen is fi-ecjuently of a ditferent shape in the two sexes. In many 

 genera the male al)domen is deeply hilid oi' bilobed 

 at tip, while the female has the tip entire. In 

 some forms it is more bitid in the female. In 

 some cases the tip is provided with foliaceous 

 plates or lamelhe. In a few genera there are two 

 forms of the male; in one the mandil)les and ante- 

 rior legs ai'e enlarged. 



The development and life history of the' bird- 

 mites are replete with reniarkable facts — facts which have jnizzled 



investigators for years, and even now 

 not thoroughly understood. The 

 egg is comi)aratively large, elongate, 

 and slightly curved. The newly- 

 hatched larvie have six legs, hut in 

 some forms apparently but four. It 

 has been claimed that it is the third 

 pair of legs that is added when the 

 larva transforms to the nymph. The 

 nymph has the general form of the 

 adult, but lacks the genital organs. 

 In certain species there is a Inqoopial 

 stage developed from the nymi)h. It 

 is distinguished from the nymph by 

 the absence of mouth-parts, and by 

 having long hairs, instead of a claw, 

 at the tip of leg IV. This stage has 

 on the venter an area of sucking disks 

 similar to that of the Ilypopaxoi the 

 Tyroglyphida'. The adult male is 

 developed from the nymph. But in tlni ca.se of the female there is a 

 passage form })etween the nymph and the true adult female. It has 



Fig. 170.— Pterolichus sp. (near deliba 

 tus), on condor. 



