4 
Introduction 
The result was a systematic, bibliographical, and morphological revision of 
the family with illustrations of all of the known species. 
Adaptations to an ectoparasitic life. Polyctenids resemble ectoparasitic 
Diptera of the family Nycteribiidae in general appearance. Among the 
special adaptations for a life amidst the fur of mammals may be mentioned 
the ctenidia, absence of eyes and ocelli, flattened body form, reduc¬ 
tion of wings to mere paranotal pads, enlargement and occasional asym¬ 
metry of claws, and an entirely unique combination of paedogenesis and 
“pseudo-placento” viviparity analogous to that of African earwigs of the 
genus Hemimerus which live as ectoparasites on rats of the genus Cricetomys. 
Although these characters immediately set the Polyctenidae apart from all 
other Hemiptera it must be remembered that the extreme specialization 
seen in the Polyctenids, Platypsyllid beetles, fleas, lice, and pupiparous 
Diptera has directed certain characters along parallel lines resulting in this 
superficial but striking convergence. 
Systematic position. In fundamental characters there is little doubt 
that the Polyctenidae belong near the Cimicidae and Anthocoridae in the 
great superfamily Cimicoidea. They scarcely conform to Reuter’s super¬ 
family diagnosis but the number and arrangement of scent glands and the 
strikingly asymmetrical male genitalia are identical with those of the 
Cimicids and Anthocorids, trichobothria are absent in the entire group, 
and other characters such as the ovipositor of certain Anthocorids and the 
organ of Berlese of female Cimicids occur only sporadically in the Cimi¬ 
coidea. The antennal segmentation is correct for the Cimicoidea and the 
first rostral segment is reduced as in Anthocorids but may be seen in some 
forms and indicates an original four-segmented condition. Most peculiar are 
the apparently four-segmented tarsi in contrast to the typically three- 
segmented condition in most other Hemiptera with occasional reductions 
to two or one-segmented tarsi. 
Geographical distribution and host relationships. Distributional and host 
data were assembled in 1939 by Ferris and Usinger but their interpretation 
was hampered for want of a clear exposition of the phylogenetic relation¬ 
ships of bats. Since that time a very lucid book entitled “Bats” has ap¬ 
peared from the pen of an authority on these animals, G. M. Allen. Facts 
gleaned from this book go far toward solving the perplexing problems in 
Polyctenid distribution. 
The new world Polyctenidae (Table I) are sharply distinguished from 
their old world relatives, belonging to the single, compact, and relatively 
slightly modified genus Hesperoctenes. Species of this genus have been found, 
with but a single exception, on bats of the family Molossidae and all except 
two of the parasite species have thus far been recorded from but a single 
species of bat. In striking contrast to this, the old world Polyctenidae fall 
into several very distinct genera, all relatively highly modified for an 
