Folia Historico-Naturalia Musei Matraensis - A Mátra Múzeum Természetrajzi Közleményei 21. (1996)

placed more to the centre in the direction of the longitudinal axis of the tarsometarsus. The crista lateralis hypotarsi is located on the lateral edge of the plantar side, and bends outwards into lateral direction. The tuberositas musculi fibularis brevis can not be found, and hence the fossa parahypotarsalis lateralis is not formed. At the proximal end of the bone the fossa infracotylaris dorsalis is wide and long, the foramina vascularia proximalia are standing well apart, and are placed in one line. The tuberositas musculi tibialis cranialis in dorsal view are lying in medial direction from the longitudinal axis, while in the members of the Accipitridae family these are located in the line of the longitudinal axis, or placed in lateral position from it. In other birds of prey near to the distal end of the bone on the dorsal side there is a considerably big foramen, namely the foramen vasculare distale. In the Falcons there are two very small foramina that open on the plantar side at the same point. The trochlea metatarsi IV in proximal direction is located more to the back (the os metatarsale IV is shorter) and the trochlea metatarsi III in distal direction is located more to the front than in the Accipitridae and Pandionidae species. As a consequence in the Falcons the trochleae in dorsal view are located along an arch, in other birds of prey along a straight line. From distal view the trochleae are placed along a more arched line than in the Accipitridae species. DESCRIPTIVE PART Cranium Regarding their size the skull of the Eleonora's Falcon is the biggest, the second is the Hobby's and the Kestrel's and that of the Merlin is a little bit smaller. The cranium of the Red-footed Falcon and the Lesser Kestrel is considerably smaller, their longitudinal measurements do not overlap with that of the former species (Plate IV, Figure 2). On the basis of their size they can be easily separated from the former species. In the case of the Eleonora's Falcon I had only an individual of unknown sex, where GL=51.4 mm, GW=30.3 mm. The GL/GW value is 1.70. The rank of the species according to the length of the cranium measured without the beak (CL) is the following: F. tinnunculus > F. subbuteo > F. columbarius > F. vespertinus > F. naumanni There is a considerable difference between the sexes in the case of the Hobby and Merlin. The females are considerably larger, in the case of the Hobby the longitudinal measurements of the sexes do not overlap at all, in the Merlin they overlap only to a small extent. In the case of the Kestrels there is only a slight difference in size, the females are a bit larger (Plate IV, Figure 2). Regarding its relative size the beak of the Hobby is larger and more robust, and measured at the nostrils wider than that of the other species. The nostrils themselves are located more apart than in the Merlin and Kestrel. Among the cranium of the Hobby and Merlin the beak size is the most reliable differentiating marker. Relatively both the Red-footed Falcon and the Lesser Kestrel have larger beaks as compared to the Merlin or the Kestrel (CL/RL values are low). The neurocranium of the Kestrel is the biggest among the examined species (from the Eleonora's Falcon I did not have adequate material). In the case of the true Falcons the size of the beak relative to the body size is larger in the females than in the males (Plate IV, Figure 2). The cranium relative to its width is higher in the Merlin than in the Hobby. The Kestrel and the Red-footed Falcon are in intermediate position between the former species. The cranium 17