106. =Back of tarsus= (_Planta tarsi_). Homologically the =Sole=
(_Planta_).
107. =Heel= (_Calcaneus_; _Talus_). The upper posterior extremity
of the tarsus.
108. =Spur= (_Calcar_). Any bony sharp process or spine implanted
on the tarsus, as in the rooster.
109. =Scutellæ= (_Scutella_). The succession of small, usually
rectangular plates, applied against the anterior face of the
tarsus, and the upper surface of toes. These sometimes encircle
the tarsus completely, meeting on the inner side; sometimes
reach half round with similar half-rings on the back side of the
tarsus; are sometimes divided into polygonal plates; are sometimes
fused into a continuous plate, either anteriorly or laterally.
Modifications of structure in this respect indicate differences in
rank and systematic position of the highest value.
110. =Scutellate tarsus.= When the tarsus is covered with
transverse or polygonal scales, as described above.
111. =Booted tarsus.= Where the anterior face is covered with a
continuous horny plate not divided into scutellæ.