THE ACAEINA OR MITES. 



25 



Trouessart has separated the group of Cunaxa from the Bdellidae and placed them 

 as a family of Trombidioidea; this does not appear natural to me. Of Cunaxa three 

 species have been described in the United States; they live in damp places and are 

 very active. This genus (Cunaxa) was formerly called Scirus, but the type of Scirus 

 is very close to the true Bdella. Of Bdella we have a number of species, and some are 



Fig. 21.— Bdella peregrina. (Author's illustration.) Fig. 22.— Bdella tenella. (Author's illustration.) 



common. They usually inhabit moist places, moss, rotten bark, etc. One species 

 (B. marina Packard) is common along the North Atlantic shore between tide marks. 

 . B. cardinalis Banks and B. peregrina Banks (fig. 21) are common on damp soil; B. 

 tenella (fig. 22), under rotten bark; B. utilis Banks, with scale insects. Michael has 

 recorded finding a species of Bdella on the web of a tube-weaving spider, Amaurobins 

 ferox Blackw. The mites were not disturbed by the 

 spider and evidently felt much at home. They doubtless 

 fed on some of the small insects disdained by the spider. 

 Ewing has found several species under the loose bark of 

 trees in Illinois, where they feed on the tyroglyphids and 

 CoUembola. Scirus can be used for that section of Bdella 

 which has the last joint of the palpi long and cylindrical; 

 Bdella, for those with this joint short and widened at tip. 

 Molgus is used by some authors for the long-palpi species 

 with numerous bristles on the mandibles. Several of our 

 species described in Bdella will thus belong to Scirus. 

 similar to Bdella; oui one species (C americana Banks) occurs in damp fields; it was 

 formerly known as Ammonia, which name is not only later but also preoccupied. 

 The genus Pseudocheylits of South America has the claw-tipped palpus of Cunaxa 

 but with a very much shorter claw. 



Fig. 23.— Mandibles and pal- 

 pus of Cunaxa. (Author's 

 illustration.) 



The genus Cyta is very 



