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Show 78 MR. F. E. BEDDARD ON THE [Feb. 19, trinse of the family Falconida.), 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 . Gurney2. The Accipitres have been divided by Prof. Huxley3 into three groups-(1) Cathartidse, (2) Gvpaetidse, (3) Gypogeranidse-on the characters of the skeleton. Prof. Garrod's investigations4 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 Cathartidae the ambiens, semitendinosus and accessory semitendinosus, and femoro-caudal are present, the formula being on Garrod's system A X Y + . In the Gypaetidse (termed Falconidse) the muscles present can be indicated by the formula A + . In the Gypogeranidse (Serpentarius) the formula is B X Y + . These muscular divergences led Prof. Garrod to remove Serpentarius and the Cathartidse 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 Gypaetidse. I 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 (Falco eesalon), 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 Gypaetidse is, as stated by Garrod, A -f. Polyboroides 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, & c , and should be referred to the Gypaetidse and not to the Gypogeranidse. In examining the muscles of the wing I have compared Polyboroides with Serpentarius, Cathartes, and with Gypohierax as a type of the Falconidse. The tensor patagii brevis5 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. 8 ' A List of the Diurnal Birds of Prey,' &c. (London, "Van Voorst), p. 18. 3 " O n the Classification of Birds," P. 2. S. 1867, p. 462. 4 "On certain Muscles in the Thigh of Birds, and on their Value in Classification," P. Z. S. 1873, p. 634. 5 These muscles were dissected in another specimen. |