ART. 30 NEW PAKASITIC MITES EWING 9 



Remarks. — Description based on five females taken from the type 

 host, a black snake, from type locality, by E. E. Stadelman, Sep- 

 tember 29, 1927. This species differs from H. americanus., new 

 species, in the characters of the chelicerae, the shape of the sternum, 

 and a few other particulars. 



Family DERMANYSSIDAE 



Subfamily LiPONYSSlNAE 



Genus TETRAGONYSSUS Ewing, 1923 



Body stout but longer than broad and clothed with spinelike setae ; 

 dorsal plate large, undivided. Chelicerae reduced, pointed as if for 

 piercing. Sternal plate very broad, with three pairs of stout setae 

 and tending to ankylose with endopodal plates; genito ventral plate 

 large but not reaching anal plate; anal plate subtriangular, with two 

 anterior, paired setae and one posterior, unpaired seta. Legs stout, 

 particularly the first and second pairs ; femora I and II enlarged and 

 bearing dorsally long, stout, spinelike setae ; tarsal claws small. 



Type species. — Liponyssus gigas Oudemans, 1912. 



Remarks. — This genus is very near Myonyssus Tiraboschi, 1904, 

 and it is probable that it will need restriction in the future to char- 

 acters some of which have in the past been considered as specific for 

 its type species. 



TETRAGONYSSUS MICROTI, new species 

 Plate 3, Figuue 3, 4 



Female. — Body short, almost subcircular. Chelicerae rather stout ; 

 movable chela curved and irregularly bifurcate at tip; fixed chela 

 almost straight and ending in a minute, strongly curved, sharp hook. 

 Sternal plate in the form of a strongly curved arch; sternal setae 

 large, arranged in two diverging rows. Endopodal plates well 

 sclerotized, extending forward and matching sternal plate; endo- 

 podal setae similar to sternal setae. Genitoventral plate large, about 

 as broad as long, bearing four pairs of setae, the anterior pair being 

 discal and the others marginal. Anal plate small; anus situated near 

 front margin of anal plate; anal setae large, subequal, the unpaired 

 one situated at apex of anal plate. Legs very stout; posterior pair 

 longest; each femur and patella of the first two pairs of legs with 

 conspicuous dorsal spines; coxae large, without peglike spines. 

 Length, 0.51 mm; width, 0.38 mm. 



j/«7e.—Sterno ventral plate about twice as long as its greatest 

 width, width at sternal region equal to width at abdominal region, 

 narrowest between the posterior coxae. Movable chela of chelicerae 



