THE ACAEIXA OR MITES. 



77 



expansion at the tip of the body, by which she retains hold of the skin of the bat. 

 Only a few species are known. 



Kolenati described several allied genera, but most, if not all, are based on immature 

 gtages of species of Spintumix. 



Fig. 14&.—Dermanyssus galUnae: g, 

 Caroncle; m, beak; v, anal plate, 

 (Author's illustration.) 



147. — Liponyssus americanus. (Author's 

 illustration.) 



The one species of Ptilonyssus occurs on sparrows. The legs are but little bristly and 

 not as hea\y as in the other genera. Two species of Sternostomum are known — one 

 on the swallow, the other, 5. rhinolethrum Trouess. (fig. 140), on the domestic fowl. It 

 occurs in the nasal fossae, sucking the blood of its host, and continues to feed long after 

 the death of its host. Zurn and Weber consider 

 that it is the cause of a catarrhal inflammation 

 in the fowls. Rhinonyssus is similar in structure 

 and habit and occurs in other birds. 



The genus Anq/stropus, whose species was found 

 on bats, is also related to Sternostomum, but leg I 

 is without the caroncle and is very much enlarged, 

 so it may be a distinct genus. Dr. E. Trouessart 

 has united these genera {Rhinonyssus, Ptilonyssus, 

 and Sternostomum) in a special subfamily, the 

 Rhinonyssin.T, based on the dorsal position of the 

 peritreme. None of these forms has, as yet, been 

 taken in the United States. 



The Halarachninse include but two genera — 

 Balarachne (fig. 144), which inhabits the bronchial 



passages of seals, and Pneumonyssus (figs. 141, 142, 143), which occurs in the lungs of 

 old-world monkeys. Several species of each genus are now known. //. aitenuata 

 Banks, from Alaska seals, has a very elongate body. Doubtless there are also other 

 forms in the air passages of other animals. These mites evidently cause or aggravate 



Fig. \AS>.— Liponyssus: Anal plate and 

 mandible. (Author's illustration.) 



