THE ACARINA OR MITES— BANKS. 



13 



a few simple hairs. The palpi are short and simple, four-jointed, and 



with only a few hairs. The mandibles are rather small, but distinctl}- 



chelate; in one g-enus the}' are very large. The legs are six or seven 



jointed and terminate in two simple claws, and often with a median 



plumose pulvillus. The venter has the usual openings, but in Xoto- 



jthaUiis the anal aperture is on the dorsum of the abdomen. These 



mites can run rapidly, and JEiqjodes can make considerable leaps. 



Most inhabit the ground, but some are found on the leaves of trees. 



All are predaceous and feed on various small insects or insect Qgg>^. 



They seem to delight in cold, damp places, and can be found in winter 



still active among and under fallen leaves. They are among the 



most cojumon acarians in high latitudes, and are 



also frequent in caves, both of this country and 



of Europe, where their simple and primiti\'e 



structure is well suited to the conditions. Their 



internal anatomy has lately been investigated 



l)y Nordenski(>ld, who tinds that Rluuj'id'ia is 



among the most primitive of the Trombidoidea. 



The oesophagus, which opens near the tip of 



la))ium or underlip, is very slender, and after 



passing through the large '•])rain." enters a 



very large stomach. From the upper part of 



this arises the intestine, which soon expands 



into a very large colon, opening at the tip of 



body. The eggs, as far as known, are laid upon 



the surface frequented by the adult. The larvae 



reseml)le the parent, while the nymph ditt'ers 



only in size. There is no sexual dimorphism. 



]\Iost of the connuon species vary a great deal 



in markings, the consequence being that Koch described each of the 



connuon European species under many diil'erent names, several having 



from ten to twenty synonyms. Onr forms have ])een collected only in 



the northeastern States. 



Five of the described genera occur in the United States; these may 

 lie tabulated as below: 



1. Legs extremely slender, anterior i)air luueh more than twice as long as ImkIv 



L,hiopoOts 

 Anterior leg8 nuich shorter 2 



2. Hind femora much thickened; anterior legs much longer than others — Eupoch^ 

 Hind femora not thickened 3 



3. Anal opening on the dorsum ; mandiltles small Noiophallvs 



Anal opening on venter -1 



4. 3Iandibles very large; legs longer than 1 )od y lUiagidUi 



^landibles small ; legs scarcely as long as body Tij<h'v.s 



Our one species of Linopoden is a very pretty pale yellowish or 

 reddish mite, with some white marks, one on the ])ack is in the form 



. — Venter of an* 



ErPODID. 



