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

Phalanx 2 digiti 2 posterior The phalanx 2 dig. 2 post, has approximately equal length in the Hobby, Merlin and in the Kestrel. The phalanx of the Red-footed Falcon and Lesser Kestrel is considerably smaller, and differs from the former species so much that there is no overlap between them (Plate XXIX, Figure 1). Compared to its length the corpus phalangis is the thinnest in the Hobby, and the thickest in the Kestrel. The other species are in intermediary position between these extremes, but the phalanx of the Merlin is in average (relative value) thinner than that of the Red-footed Falcon and Lesser Kestrel (Plate XXX, Figure 1). The width of the proximal end of the bone proportional to its length (GL/PW) is smallest in the Hobby, and then in the Merlin. In dorsal view the corpus phalangis of the Hobby narrows a little bit on the distal part, but equally wide in the Merlin (Plate XLIV, Figures 16-17). The sulcus intercondylaris in the Hobby is deeper than in the Merlin, and shallowest in the Red-footed Falcon and Lesser Kestrel (Plate XLIV, Figures 16-19). The corpus phalangis in lateral view is more curved in the Kestrels than in the Hobby and Merlin. This is more prominent if viewed in the dorsal contour line (Plate XLIV, Figures 20-21). In the Red-footed Falcon the corpus phalangis widens gradually in proximal direction (dorsal view), while in the other species the lateral and medial contour lines are approximately parallel, or occasionally gets wider slightly in the Kestrel (Plate XLIV, Figures 16-19). In the Kestrel the medial edge of tuberculum extensorium is tilted, while in the Hobby and Merlin is parallel with the longitudinal axis, and hence the tuberculum extensorium in dorsal view is more rectangular. In the Red-footed Falcon and Lesser Kestrel this inclination is minimal, though visible. The proximal part of faciès plantaris of corpus phalangis in the Kestrel and Lesser Kestrel is more rounded than in the rest of the species. The reason is that the crista plantaris medialis and cr. plant, lateralis are higher in these species then in the others. Furthermore as a consequence of that the higher cristae in the Kestrel and Lesser Kestrel the corpus phalangis in lateral view widen stronger in proximal direction than in the other species. This widening is already weaker in the Red-footed Falcon, in the Merlin and Hobby the corpus basically is constantly sized, only widens right prior the proximal end of the bone. In the Hobby and Merlin in lateral view the corpus phalangis narrows down on the distal section (Plate XLIV, Figures 20-21). The reason of this phenomenon is that the crista plantaris medialis and cr. plant, lateralis are missing on this section. In the Kestrel and Lesser Kestrel this narrowing is almost invisible, and in the Red-footed Falcon it is very slight. The dorso-distal edges of condylus lateralis and cond. medialis are protruding in the Hobby and Merlin, and hence on this part the capitulum phalangis is a bit pointed in lateral view. Consequently the dorsal side of capitulum phalangis is either straight or concave in lateral view. In the other species this pointedness is less pronounced (the dorsal side of the capitulum is rounded), or completely missing. In the latter case the capitulum phalangis in lateral view is more or less arch shaped, for example in the Red-footed Falcon and Lesser Kestrel (Plate XLIV,*Figures 20-21). Summary Falco subbuteo: - the phalanx is thin, the corpus phalangis on the distal section slightly narrows down (dorsal view), - the tuberculum extensorium is quadrangle, its sides are parallel (dorsal view), 55