THE AC MUX A OR MITES— BANKS. 



17 



Trouessart ha.s separated the oroup of Sdrus from the BdellicUe 

 and placed them as a family of tlie Trombidoidea; this does not appear 

 natural to me. Of Srirus ])ut one species has been descrilied in the 

 United States; it lives in damp places, and is very ai-tive. Of Bdella 

 we have a number of species, and some are com- 

 mon. They usually inhabit moist places, moss, 

 rotten 1)ark. etc. One species {B. marina Pack- 

 ard) is common along the north Atlantic shore 

 between tidemarks. B. cardinal is and B. pcr- 

 egrina are common on damp soil: B. fowJla, 

 under rotten bark. Michael has recorded rind- 

 ing a species of Bdella abundanth' on the web 

 of a tube-weaving spider, Amaarohius fero,r. 



The mites were not disturbed hy the spider and evidentlv felt much 

 at home. They doubtless fed on some of the small insects disdained 

 ])y the spider. The genus Cyta is very similar to Bdella; our one 

 species (6'. aatei'icana) occurs in damp rields: it was formerly known 

 as Amaumia, which name is not only later, but also preoccupied. 



Family CHEYLETID.E. 



The Cheyleticla? are a small family of tiny mites, differing consider- 

 ably in habits and structure among themselves. The typical forms 

 are distinguished bv the enormous palpi attached to a distinct beak. 



Fii;. Iri.— Mandibles and 



PAI.PrS OF SCIRl"i«. 



Fig. li'i. — CHEYi.ETrs sp. (pep.gande). 



]'"iG. 17. — Cheyletvs pyriformis; beak 



AND PALPUS, tip OF LEG I, AND CLAWS 

 OF LEG II. 



The palpi are three to five-jointed, and frequently have a minute mov- 

 ' able tubercle or papilla near the tip on inner side, which in some forms 

 I is tipped with one or two pectinate ])ristles. This papilla is evidently 

 ' homologous with the ""thumb" of the Trombidida?. The l)eak is plainh' 



Proo. X. JNI. vol. xxviii— 04 2 



