12 PROCEEDINGS OF THE NATIONAL MUSEUM Vol.68 



and with large, conspicuous lateral lobes; plate IV larger than III 

 and with larger lateral lobes; plate V much the largest of all the 

 pleural plates, with or without very small lateral lobes; plate VI 

 broader than long and without lateral lobes; plate VII triangular, 

 longer than broad. Legs of medium length; femur I only slightly 

 longer than broad; tibia I over twice as long as broad. Posterior 

 tubercle of femur III large, with a deep emargination next to it on 

 the inside, bearing a seta near tip longer than tubercle itself. 



Length of an average-sized, unengorged female, 3,15 mm.; great- 

 est width, 1.30 mm. 



Male. — Leg I slightly enlarged; femur I slightly longer and tibia 

 I slightly shorter than in the female; tarsus I enlarged. Setae on 

 anterior tibial thumb as follows: Chief or distal spine extending be- 

 yond the margin of thumb by half its length ; dorsal accessory spine 

 about half as thick as distal one, of the same length, and situated 

 less than its own width inside of terminal spine; outer ventral ac- 

 cessory spine setiform, twice as long as the terminal spine and situ- 

 ated directly below it; inner ventral accessory spine slightly longer 

 than terminal spine and about one-half as broad, situated consider- 

 ably inside the other accessory spines but not in the crotch of the 

 tibia. Pleural plates similar to those of female except for I and III ; 

 I is irregular in shape and much broader than long, III has low, 

 small lateral lobes instead of the conspicuous ones found in the 

 female. 



Length of average-sized specimen, 2.45 mm.; greatest width, 0.90 

 mm. 



Type host and type locality. — Ateles paniscus from (?). 



Described from very many specimens of both sexes taken from 

 " post-mortem " specimen of host species, Ateles paniscus (U.S.N.M. 

 238254), collected at Bcni, Bolivia. 



In 1922 Dr. W. M. Mann brought back with him from South 

 America two red-faced spider monkeys {A. paniscus) that were 

 grossly infested with P. consohrinus. The monkeys were presented 

 to the National Zoological Park, but within a few days one of them 

 died. This specimen Avas " pickled " in a large jar where the writer 

 observed that it was loaded with thousands of lice in all stages of 

 development, and the hairs of the host in all parts of its anatomy 

 contained countless numbers of nits. The other individual received 

 several treatments for lice at the zoological park but died within 

 a few weeks. 



Doctor Mann also brought back with him two living examples of 

 the brown-hipped marmoset {Lenotocehus nigricollis) , obtained at 

 Tumupasa, Bolivia. These were placed in the National Zoological 

 Park, but lived only a fcAV days. When they died they showed a 

 slight infestation with a Pediculiis, species, and nits in some abun- 



