NO. 3658 MALLOPHAGA—ELBEL 11 
all species except in C. robusta. Abdominal sternite II has more total 
setae in both sexes of C. bucerotis and C. robusta than in corresponding 
sexes of C. fasciati, C. lophocerus, and C. camuri; this sternite has one 
median row of setae in all species except C. bucerotis, which has three 
median rows. The male genitalia have each lateral horn possessing 
posterior points in all species except C. robusta, which has one sharp 
median point crossing the broad endomeres; the posterior points are 
sharp in C. bucerotis and C. lophocerus but rounded in C. fasciatt and 
C. camuri; C. camurt has only one posterior point instead of two as in 
the other species; the two points do not reach the slender endomeres 
in C. lophocerus, but one point crosses the broad endomeres in C. 
bucerotis (figs. 1-7). In the female the ventral sclerite between the 
vulva and anus is elevated medially between the sclerital hooks in 
C. fasciati, C. bucerotis, and C. robusta, is elevated only slightly in 
C. camuri, and is not elevated in C. lophocerus. The female anal fringe 
has the most setae in C. fasciati and the fewest in C. lophocerus. 
Clay (1958) treated populations of the ischnoceran genus Degeeriella 
as subspecies when the male genitalia were apparently identical or 
differed only in a minor degree and when there were other minor 
morphological differences. Because of similarity of the genitalia, 
Chapinia fasciati and C. camuri could be considered subspecies of 
C. lophocerus. This would express the similarity of their six host 
species, which are all members of the Ethiopian genus Tockus. Clay 
(1958) pointed out that the genitalia, particularly in the Amblycera, 
might show only minor differences throughout a genus or species-group 
and great differences in other groups. She therefore concluded that 
differentiation of the genitalia has taken place at different rates in 
different groups. Similarly, Johnson (1960) stated that evolution and 
morphological divergence would not be expected to proceed at the 
same rate for all free-living species. It would seem that the similarity 
in the genitalia of C. fasciati, C. lophocerus, and C. camuri would 
indicate either that evolution has not proceeded as rapidly in these 
species or that they have not been isolated as long as other species of 
Chapinia. Clay (1958) stated that if subspecies were populations that 
would interbreed under natural conditions if they occurred sym- 
patrically, any morphological differences which might prevent inter- 
breeding should be considered as specific characters. Johnson (1960) 
believes that there is little possibility of finding interbreeding popu- 
lations among lice which are isolated on their hosts. She stated that 
it would be desirable to treat all stable recognizable forms of Anoplura 
and Mallophaga as species. Clay (1962) consequently stated that 
the subspecific category might be useful in some of the ischnoceran 
genera, but its application in the Amblycera is less satisfactory and 
