16 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.63, 



thorax with straight, posteriorly divergent sides, and about as large 

 as the prothorax. Abdomen broad, oval, with serrate margins and 

 well clothed, with large conspicuous setae. Gonopods of female low, 

 inconspicuous but fringed with conspicuous setae, the inner two of 

 which are stouter than the rest. Genital armature of male large, 

 conspicuous and well chitinized; basal plate long and broad with 

 straight sides that diverge posteriorly; parameres short and stout, 

 mandiblelike. In the female, legs subequal; femoral tenaculum 

 single-lobed ventrally and bilobed dorsally, with crotch conspicuously 

 lined, or furrowed. In the male, front legs (pi. 1, fig. 2) larger than 

 the rest and each provided with a clasper formed of the tarsal claw 

 and a long thumb from the first tarsal segment. This thumb is 

 fully as long as the claw, broadest at its base, and bears a single 

 small seta near its tip. 



Length of female, 1.58 mm. ; width, 0.74 mm. Length of male, 

 1.50 mm. ; width, 0.67 mm. 



Type host and type locality. — From Gtenomys^ species, Tucuman, 

 Argentina. 



Description based on two females and one male combed from a 

 female skin of Ctenomys opimus (Cat. No. 121168, U.S.N.M.) 

 from Oruro, Boliva. Neumann had a quantity of males and females 

 collected on Ctenomys, species, from Tucuman, Argentina, by F. 

 Lahille. 



GYROPUS POLLICARIS, new species. 



Plate 1, fig. 3. 



Quite similar to G. forflculatus Neumann, but more slender and 

 differing in several minor characters. Head as broad as long, with 

 posterior margin almost semicircular; antennal fossae deep, ventral 

 borders more deeply notched than dorsal; last segment of antenna 

 with a straight lateral margin and broadly and evenly rounded in- 

 wardly and posteriorly; palpi conspicuous, each with its four 

 segments clearly demarcated, second segment as broad as first. 

 Prothorax not so broad as head and almost twice as broad as long. 

 Mesothorax the narrowest region of the body. Metathorax with 

 straight, posteriorly divergent sides. It is about equal to prothorax. 

 Abdomen fully twice as long as broad and clothed with conspicuous 

 setae. Male genital armature large, well chitinized and compact; 

 basal plate over twice as long as its greatest width, its straight sides 

 diverging posteriorly; parameres not mandible-like. Legs rather 

 stout, the anterior pair of male slightly stouter than the others and 

 with well-developed tarsal thumb. Tarsal thumb (pi. 1, fig. 3) 

 as long as claw and gradually increasing in width from apex to 

 base, laterally with two setae, the one near the apex being the smaller. 



