84 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 95 
siderably to our knowledge of this difficult but fascinating group of 
insects and laid a secure foundation for future work. 
A most regrettable error was made in my 1936 report regarding the 
measurements given there. Ad/ measurements given are too small, 
owing to an error made in calibrating the eye-piece micrometer with 
the stage micrometer, which consisted of 1.1 mm. instead of 1 mm. 
as I had supposed. All these published measurements may be cor- 
rected by multiplying each by the constant 1.084. In the present re- 
port, as well as the first, all measurements were made by means of the 
eye-plece micrometer. All measurements used are in millimeters, and 
all drawings were made by me. 
I take this opportunity of expressing my thanks to Dr. Alexander 
Wetmore, director of the U. S. National Museum, for his permission 
to study all the Mallophaga collected while engaged in ornithological 
explorations for that institution in Mexico and Colombia, and for his 
assistance and encouragement during the preparation of this report, 
as well as that given me by Dr. KE. A. Chapin, curator of insects in 
the same institution. I also extend my appreciation to Dr. G. H. E. 
Hopkins for his generous cooperation and helpful criticisms from 
time to time, especially in having fresh material compared with the 
old types of Piaget and others, thereby establishing certain identifica- 
tions beyond question. 
Suborder AMBLYCERA Kellogg 
Family MENOPONIDAE Mjoberg 
Genus MENACANTHUS Neumann 
MENACANTHUS NOTHOPROCTAE, new species 
FIGuRE 1, a—-c 
Types.—Male and female, adults, from NMothoprocta cinerascens, 
collected by the author at Villa Montes, El Chaco, Bolivia, November 
6, 1936; in collection of author. | 
Diagnosis.—Closely related to M. arctifasciatus (Piaget), taken on 
Rhynchotus r. rufescens and R. rufescens maculicollis, the female dif- 
fering chiefly from that species in the size and proportions of the body 
segments, shape of head, different shape of last abdominal segment, 
and its chaetotaxy, as well as the chaetotaxy in general of the abdo- 
men, the present species having the hairs, both dorsal and ventral, 
shorter and fewer. 
The male of /. arctifasciatus not having been taken by either Piaget 
or myself, no comparison can be made of the genitalia, which will no 
doubt prove to be distinct. 
