12 PEOCEEDIISrGS OF THE NATIONAL MUSEUM VOL. T7 



and fringed with close-set hairlike setae. Ventral abdominal setae 

 swollen at their bases and tapering to an exceedingly fine point; 

 patches of setae on the sternites of abdominal segments five to seven. 



Legs not stouter than usual for the genus ; femora II and III each 

 with a patch of spines on the anterior margin at the base ; each coxa 

 of posterior pair of legs set in a coxal cavity formed by the posterior 

 border of the metathorax and the lateral borders of the first two 

 abdominal sternites. Pseudosegmentation of tibiae all but wanting. 



Length of female, 3.75 mm. ; width, 2.10 mm. 



Type host. — Mim^opus apus. 



Described from a single female taken from the chimney swift, 

 Chaetura pelagica, Columbus, Ohio, June 9, 1899, by Prof. J. S. 

 Hine. This is the only specimen that to the knowledge of the writer 

 has been taken of this rare species in North America. Mr. H. S. 

 Peters has already reported (Peters, 1928) on the taking of this 

 specimen in Ohio. 



There may be some doubt about the identification of this specimen 

 from our American chimney swift as Eureum cimicoides. It agrees 

 well with the very good description and figures of Denny which were 

 based on specimens taken in England. 



If this identification is correct, how are we to explain the presence 

 of this louse on our chimney swift, a species of a different genus from 

 its European host and occurring in a different continent? One 

 hypothesis is that our chimney swift has obtained the species through 

 host transfers in recent geological times from the western Chaetura 

 vauxi and the Siberian representative of the genus Chaetura. This 

 is, of course, a mere speculation. It may possibly have persisted 

 since the days of a common ancestor of Micropus and Chaetura on 

 descendants in both of these genera. 



Genus HIRUNDOECUS, new genus 



This genus is a very distinct one and in fact has but little in 

 common with Dennyus., as is clearly indicated in the key already 

 given. Some other generic characters should be mentioned. The 

 prothorax is not at all of the Dennyus type, but is of the type of 

 such genera as Menopon and Ancistrona; that is, it has a very broad 

 pronotum with an outwardly, almost evenly rounded margin. The 

 mesothorax is distinct and separated from the metathorax by a 

 dorsal suture, but is reduced until it is scarcely one-fifth the size of 

 the metathorax. The genital armature is of much the same type as 

 in Dennyus, but the basal plate is broader. The endomeres are 

 united and poorly developed. 



The closest affinity of Hirundoecus appears to be with certain 

 species of Menopon, those of the type of M. loomisii Kellogg and 



