78 MR. F. E. BEDDARD ON THE [Feb. 19, 
trinee of the family Falconide), and by G. R. Gray’, is, as Milne- 
Edwards acknowledges, in the main Justified by the osteological 
characters; Milne-Edwards, however, considers that its peculiarities 
necessitate the creation of a separate subfamily for its reception. 
This view is accepted by J. H. Gurney’. 
The Accipitres have been divided by Prof. Huxley* into three 
groups—(1) Cathartidee, (2) Gypaetidee, (3) Gypogeranidee—on the 
characters of the skeleton. Prof. Garrod’s investigations* emphasized 
the naturalness of this grouping ; he showed that these three divisions 
could be defined by the presence or absence of certain muscles in 
the leg. 
In the Cathartidze the ambiens, semitendinosus and accessory semi- 
tendinosus, and femoro-caudal are present, the formula being on 
Garrod’s system AXY+. 
In the Gypaetidee (termed Falconidze) the muscles present can be 
indicated by the formula A+. 
In the Gypogeranide (Serpentarius) the formula is BXY +. 
These muscular divergences led Prof. Garrod to remove Serpen- 
tarius and the Cathartide from the Accipitres and to associate them 
with other birds. Without following Prof. Garrod in this latter 
alteration of existing arrangements, it must certainly be admitted 
that his results entirely justify the breaking up of the Accipitres 
into the three groups already indicated. 
I do not, however, find myself able to agree with Prof. Garrod in 
believing that the absence of the semitendinosus muscle is absolutely 
distinctive of all the Gypaetide. 
IL have found this muscle in Falco subbuteo, where it was rather 
feeble and apparently fused at its origin with the semimembranosus, 
but it ended in a separate and perfectly distinct tendon and was 
present on both legs; in the Merlin (Fa/co esalon), where it was a 
little better developed; and finally in Circus maurus. 
Apart from these exceptions, which do not affect the classification 
of the group, the formula of Gypaetidze is, as stated by Garrod, A +. 
Polyborcides typicus possesses the ambiens and femoro-caudal 
alone of the leg-muscles, upon the variations of which Garrod’s 
system was based ; it therefore agrees with Accipiter, Circus, &e., and 
should be referred to the Gypaetide and not to the Gypogeranidee. 
In examining the muscles of the wing I have compared Polybor- 
oides with Serpentarius, Cathartes, and with Gypohierax as a type of 
the Falconide. 
The ¢ensor patagii brevis’ of each wing is a stoutish muscle which 
divides into two tendons, inserted as shown in fig. 1 (p. 79); each 
tendon is slight and thin and of equal diameter throughout. 
1 Hand-list, i. p- 38. 
* «A List of the Diurnal Birds of Prey,’ &c. (London, Van Voorst), p. 18. 
° “On the Classification of Birds,” P. Z. 8. 1867, p. 462. 
* “On certain Muscles in the Thigh of Birds, and on their Value in Classifi- 
cation,” P. Z.S. 1873, p. 634. 
5 These muscles were dissected in another specimen. 
