CIRCUS. 
The tarsus is more than twice the length of the culmen and less than 
one-third the length of the tail. The tarsal covering consists of transverse 
scutes in front and small reticulations on the sides, but larger ones with 
the appearance of irregular scutes on the back, more pronounced towards 
the toes : in immature birds the nature of the tarsal covering is obvious, 
but in the adult the tendency is to fusion ; this tendency becomes very 
pronounced in very old examples and especially in those of Circus assimilis^ 
where at the first glance the fusion both as regards the front and back 
often appears complete. 
Exactly the same thing may be seen in species of Astur (sensu lato) 
and AccipiteTy so that it is most necessary to carefully examine immature 
birds to judge this feature. 
The wing formulae of the species varies to a slight extent, and as a 
genus Strigiceps has been recognised as valid at times, and apparently is 
now by osteological workers, I would note the differences observed. 
In Circus mruginosus the third and fourth primaries are subequal and 
longest, the second and fifth little shorter and practically subequal, the 
first equal to the sixth. Such an arrangement makes a rather pointed 
wing> though the first primary is very short. 
In Circus pygargus the third primary is longest, the second and fourth 
little shorter and subequal, the first between the fifth and sixth. 
In Circus assimilis the fourth primary is longest,! the f^hird and fifth 
little shorter and subequal and the second less than the third, but much 
longer than the first, which is about equal to the sixth. 
None of the comparative proportions seem to differ to any extent that 
can be appreciated^ and as the females exceed the males, measurements of 
the males of a larger bird agree very closely with those of a female of 
a smaller bird. 
In the nestlings the toes are thin and long, but as the bird grows the 
tarsus develops in length while the toes do not correspondingly increase ; 
as a result, the legs are long and the toes are rather short, sd^ that the 
middle toe is only about half the length of the tarsus. 
In the Accipitrine group, strictly considered, the legs, wings and bill 
seem very similar, and superficially these would appear the nearest relations 
of Circus. 
Suschkin and Pycraft, however, interpose the Buteoninse between these 
groups ; this does not seem perfectly natural, so that a reconsideration is 
suggested and especially the relationship of Astur, Accipiter and Circus. 
As the authority for the genus-name, Lacepede has been commonly 
given with a reference to the Tableciu Oiscuux. I have already signified 
11 
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