_B._ Head showing muscles. 1, Beak. 2, Nostril. 3, Tongue. 4, Sublingual salivary gland. 5, Pterygoideus. 6, Stylo-hyoideus. 7, Temporal. 8, Flexor capitis inferior. 9, Rectus capitis lateralis. 10, Rectus capitis posticus major. 11, Trachelo-mastoideus. 12, Eye. 13, Mylo-hyoideus. 14, Genio-hyoideus. 15, Biventer maxilla. 16, Digastricus. 17, Rectus capitis anterior minor. _C._ Foot of hen showing tendons. 1, Flexor perforans digitorum profundus. 2, Flexor perforatus medius primus pedis. 3, Sheath at joint through which tendon passes. 4, Flexor perforatus indicis primus pedis. 5, Flexor perforatus medius secundus pedis. 6, Flexor perforatus annularis primus pedis. 7, Flexor longus hallucis. _D._ Outside view of leg of hen. 1, Biceps flexor cruris. 2, Semitendinosus. 3, Loop through which biceps flexor cruris passes. 4, Tibialis anticus. 5, Flexor perforatus indicis secundus pedis. 6, Flexor perforatus medius primus pedis. 7, Gastrocnemius. 8, Flexor perforatus annularis primus pedis. 9, Flexor perforatus medius secundus pedis. 10, Extensor longus hallucis. ] The _ligamentum tibio-fibulare_ extends from the head of the fibula, or capitulum fibulæ, to the inner surface of the external crest, or crista externa tibiæ, of the tibia (Fig. 25, No. 3). The _ligamentum interosseum_ is a delicate ligament located between the tibia and fibula (Fig. 25, No. 4) which very early becomes ossified. =Ligaments of the Tibio-metatarsal Joint= (Fig. 16).—The tibio-tarsal joint is made up of the tibia and metatarsus. The _ligamentum capsulare ossis tibio-metatarsi_ connects the tibia and the metatarsus and surrounds the joint (Fig. 16, Nos. _A_, 7 and _C_, 7). The _ligamentum externum_, a long strong ligament, originates on the upper and outer surface of the external condyle, or condylus externus of the tibia and is attached to the upper rim of the os metatarsi (Fig. 23, No. 15). The _ligamentum anticum_ is spread out between the fossa intercondyloidea of the tibia and the tuberculum ossis metatarsi of the proximal end of the metatarsus (Fig. 16, No. _C_, 3). Just posterior to this ligament, there is an interosseous ligament, the _ligamentum interosseum_. A semi-lunar pad of fibrous cartilage, the _cartilago semi-lunaris_ is located between the outer distal extremity of the tibia and upper articular surface of the metatarsus (Fig. 16, No. _C_, 6). Its concave portion is directed anteriorly and receives an insertion from the ligamentum externum, or external ligament. The tendon Achillis (Fig. 16, No. _A_, 1) may become ossified. =Ligaments of the Toes= (Fig. 16).—In addition to the capsular ligaments, which all true joints have, we find the following in connection with the toes: The _ligamentum superius_ and the _ligamentum inferius_ connect the second toe with the great toe, or hallux.