THE ACAEINA OR MITES. 



119 



with a T-shaped process in front of the body as Acrotx)carus mirabilis Banks. The 

 principal genera may be distinguished as follows: 



1. Tarsi veiy short, ending in a long-stalked clavate sucker Hemisarcoptes. 



Tarsi usually much longer than preceding joints, ending in a pointed or lobed 



sucker 2 



2. Male with anal suckers; cephalothorax with long bristles; tarsal suckers 



cordate; mandibles chelate Canestrinia. 



Male without anal suckers 3 



3. Tarsal suckers cordate; mandibles with only one toothed jaw; genital aper- 



ture behind coxse IV Linohia. 



Tarsal suckers lobed; mandibles chelate; genital apertures between coxae 



IV or in fi'ont of them Coleopterophagus. 



Berlese has divided Canestrinia into four 

 subgenera according to the family of the host- 

 beetle. 



Family ANALGESICS. 



The bird mites ( ' * Sarcoptides plumicoles ' ' of 

 Megnin) form one of the largest and best-known 

 groups of the Acarina. Since the specimens 

 can be found on the skins of buds, collections 

 have been made in various museums, so that 

 many species native to tropical countries are 

 described — a condition not existing in other 

 groups of mites, except the Ixodidae. The 

 species in the United States, however, have 

 been but little studied. The body of an anal- 

 gesid (fig. 246) is more or less elongate; the 

 skin is soft and transversely wrinkled; in many 

 forms there are finely granulated dorsal shields, 

 one anterior and a longer posterior one; there 

 are neither eyes nor stigmata; there is usually 

 a distinction between cephalothorax and abdo- 

 men. In front there is a conical projection, 

 the rostrum; the upper part of this is known as 

 the epistoma, and is continuous with the dor- 

 sal surface of the body. Beneath the epistoma 

 are a pair of triangular simple mandibles, which 

 often project beyond it. The mandibles are 

 commonly chelate, and finely toothed at the tip. Below the jaws are a pair cf 

 maxillae, wliich bear on then outer side the simple three-jointed palpi. Below this 

 is the lower lip, and between the two is a ligula or tongue. The legs are commonly 

 ehort and stout; they are arranged in two groups, the anterior pairs close to the mouth 

 parts, the posterior pairs toward the end of the body. From then insertion on the 

 venter there extend inward chitinous brown rodlike pieces, the epimera, which form 

 a framework or skeleton for the attachment of muscles and support of the legs. The 

 legs are of five joints, the last ending in a cup or saucer shaped sucker, caroncle (fig. 

 247), or ambulacrum, and sometimes with one or two claws. The legs bear a few 

 hairs or bristles in a definite arrangement. The two hind pairs of legs often differ in 

 the sexes, and in the male one leg is often enlarged or longer than the other and used as 

 claspers. Sometimes there are projections or apophyses on the legs. In some forms there 

 is a backward projection from some of the basal joints of leg I; these are the olecranon 

 processes. On the dorsum are stiff bristles, the size and arrangement of wliich afford 

 good specific characters. The vulva is situated between the bases of the third and 

 fourth pairs of coxae; it is usually marked by a curved line, which is termed the l}Ta. 



Fig. 245. — Hemisarcoptes mains: Female. 

 (Original.) 



