74 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXVIII. 



Beak a.vd claw of i'ediculoide.s. 



Family TARSONEMID.E. 



This is a sintill family, but of much )>i()l()o-iciil and economical inter- 

 est. They are soft-bodied mites, and in some ways resemble the 



Tyrog-lyphidie, but the females dif- 

 fer from them, as well as from all 

 other acarians, in having' l)etween 

 legs I and II a prominent clavate 

 oi'gan of uncertain use. The mouth- 

 parts are formed for sucking, and 

 the mandibles are very slender and 

 needle-like. The palpi are minute 

 and barely visil)le. There are tra- 

 chea^ which open on the ventral sur- 

 f;UH> near the l)ase of the rostrum. 

 The legs are short and composed of 

 live or six joints; the anterior tarsi 

 tei'minate in one claw, the others 

 usually have two claws and often a 

 sucker. The posterior pairs of legs 

 are quite remote froin the anterior 

 pairs: in the males of Tari^ouemus ihay are almost at the tip of the 

 body. In some species the abdomen sho\vs traces of segmentation by 

 the presence of a few^ transverse lines on the dorsum. The anal open- 

 ing is at the end of the body; the genital 

 opening in TarscmemvH is a small, elongate 

 aperture near the hind coxa?. The l)ody 

 and legs are provided with a few simple 

 hairs. In several genera of the family, 

 notably in THt'xoncinnx^ there is a marked 

 difference in the structure of the sexes. 

 In the male Tarsoneinus the body is much 

 shorter than in the female, the hind legs 

 are thick and heavy, and end in a ^'er^' 

 large claw. In the female the hind legs 

 are very slender and delicate, and termi- 

 nate in two long hairs, one of them often 

 as long as the entire leg. In the mature 

 female of Pcd!eiiIoides the abdomen be- 

 comes enormoush" swollen so that it is )iO 

 to 1(>() times greater than the rest of the 

 body; the whole animal appearing as a 

 white spherical grain, with a tiny scar on one side. The male of 

 Pcdlcnloidcs has almost no abdomen at all; the body being very short, 

 an 1 angulate l)ehind. The head in this genus is almost a distinct 



Fig. 144.— Pediculoides ventricosus, 



FEMALE. 



