MITES OF SUBFAMILY HAEMOGAMASINAE — KEEGAN 231 



palpi as in adults. Legs as in adult female ; may be relatively shorter. 



Size. — Michael (1892) gave the length of the female as 940]u, width 

 510/1 ; length of male 720/i, width 400/x. Oudemans (1913) gave the 

 following measurements for the species : Female : length 1,000/x, width 

 600)11 ; male : length 850)n, width 460/i ; nymph : length 735/x, width 405/*. 

 Seven female specimens from Europe varied from 882/i, to 1,036/t in 

 body length and 490/* to 588/* in body width. Mean length was 952/i, 

 mean width 558/i. In a series of 66 females from North America body 

 length varied from 700/* to 1,078/*; mean was 871/t. Forty-nine fe- 

 males varied in width from 420/i to 672/t ; mean was 515/*. Eight male 

 specimens varied in length from 658/* to 882/*; mean was 773/*. Six 

 males varied in width from 327/* to 560/i; mean was 425/*. Five 

 nymphs varied in length from 518/i to 728/*, and in width from 336/* 

 to 448/*; mean length was 605/i; mean width was 400/i. 



Discussion. — Several factors contributed to the lengthy synonymy of 

 this species. The original descriptions of Thorell (1872) and Koch 

 (1878) are so indefinite that it is impossible to determine from them 

 even the genus to which the described species belongs. Accordingly, 

 when Michael (1892) published his description of Haemogamasus nidi 

 this was accepted as the original description of the species. It was 

 not until this manuscript was near completion that Dr. E. W. Baker, 

 of the U. S. Bureau of Entomology and Plant Quarantine, forwarded 

 to me a photostat of Tragardh's 1910 paper with the comment that the 

 species described and figured as Eulaelaps amhulans (Thorell, 1872) 

 appeared to be a member of the Haemogamasinae. The figures and 

 description left no doubt that the species was synonymous with 

 Michael's nidi. The earlier references of Thorell ( 1872 ) , Koch ( 1878 ) , 

 and Tragardh (1902 and 1904) were then examined, and it was dis- 

 covered that Tragardh had studied the specimens described as Der- 

 manyssus mnbulans by Thorell and as Gcnnasus ovalis by Koch and 

 had found them to be synonymous. He transferred the species from 

 the genus Laelaps to Eyyoasf'is in 1904 and to Eulaelafs in 1910. 



Distinctive features of female specimens of E. ambidans taken in 

 Europe may be summarized as follows: Dorsal shield not entirely 

 covering dorsal surface ; many dorsal setae barbed ; usual apical setae 

 clearly largest on shield. Dorsal body setae barbed. Tritosternum 

 barbed ; presternal area with spines. Sternal shield rectangular ; only 

 anterior pair of sternal setae barbed; anterior pair of sternal pores 

 nearly parallel with anterior margin of shield. Genitoventral shield 

 flask-shaped ; 75-80 accessory setae, all of which are posterior to usual 

 genitoventral setae. Five accessory setae on anal shield. Epistome 

 relatively narrow, with about 12 fimbriae on each lateral margin. 

 Fixed chela with a bifid tip, one tooth, and a distal and a proximal 

 seta. Movable chela with two teeth and a basal fringe of tiny setae. 

 Maxillary setae barbed. Most setae on legs barbed. 



