128 



REPORT 108, U. S. DEPARTMENT OF AGRICULTURE. 



Lahidocarjpus has an elongate, tapering body, annulate with many narrow ridges, 

 and at once reminding one of the Eriophyidae, to which there is, doubtless, some 



affinity. 



Family SARCOPTID^. 



The itch mites ( ' ' Sarcoptides psoriques ' ' 

 of Megnin) have long been familiar through 

 their disgusting parasitism of the human sub- 

 ject. They often burrow within the skin 

 of man and other mammals, and thereby 

 produce intense itching, and a diseased 

 condition known as scabies, mange, or 

 more properly acariasis. The mites are very 

 small, white, and semiglobular in shape. 

 The body is entire, and the surface trans- 

 versely striated and pro^^.ded with a few 

 bristles, often short, stout, and sharp 

 pointed. The legs (fig. 266) are short and 

 stout, arranged in two groups. The anterior 

 legs are usually larger than the others. The 

 tarsi commonly terminate in a stout claw. 

 There is generally a long pedicellate sucker, 

 sometimes with a jointed pedicle. The claw 

 or sucker may be absent and in its place a 

 Fig. 2m.-Listrophorus validus. (Original.) ^^^^ bristle. The legs often show a chitinous 

 framework of rings, both transverse and oblique. On the front of the body is a promi- 

 nent beak. The palpi are small, three-jointed, and appressed to the sides of the beak 



Fig. 2(SA.—SaTCoptes scabci: Male. Fig. 2i\ry.—Sarcoptcs scabci: Female. 



(Author's illustration.) (Author's illustration.) 



beneath. The mandibles are chelate ' and vary in length mth the genus. The 

 ventral openings are in the usual position, and in the male there is often a pair of 



J Fiirstenborg in his great work, Die Kratzerailben Menschen, figures two pairs of chelate mandibles. 



This is a manifest error and weakens one's faith in his fine figures. 



