It would appear from casual references in literature that the seals and their relatives are quite commonly infested with certain mites which occur in the nasal passages or even in the bronchial tubes. Although there are several such references, apparently in but three have the mites been named. In these three cases they have been referred to the Gamasid (or Dermanyssid) genus Halarachne. The first species, Halarachne halichoeri Allman, from Halichoerus gryphus, an Atlantic seal, was described in 1847; the second, H. americana Banks, from Monarchus tropicalis, which is also an Atlantic species, was described in 1896; the third, H. otariae Steding, from Otaria californica (which is known to American mammalogists as Zalophus cali-fornianus), was described in 1923. The specimens upon which this last species was based were obtained in Germany, although the host is a native of the west coast of North America.