1882.] DR. GADOW ON THE ANATOMY OF PTEROCLES, 319 
bankiva and in Penelope superciliosa, whilst in our common Domestic 
Fowl it is generally present. In the Pigeons it is often absent. 
If present, this muscle arises with a long but narrow and fleshy 
belly from the anterior plane of the angle between the lower end of 
the fibula and the middle third of the tibia; its strong tendon then 
passes laterally over the joint and is inserted into the proximal 
margin of the plantar tarso-metatarsal bone, near the external 
malleolus. When contracted, the muscle bends the tarso-metatarsus 
slightly dorsad and inwards. 
M. gastroenemius.—This large muscle consists in Péerocles of two 
parts, each of which arises with two distinct heads (fig. 2) :— 
Lateral posterior view of the gastrocnemius muscle of right side of 
Pterocles arenarius. 
I. Median part. 
a. Cap. tibiale: from inner and anterior aspect of the head and 
neck of the tibia, blending with the tendons of the m. femoro- 
tibialis. 
b. Cap. femorale: from hinder aspect of the intercondyloid 
region, and at the same time from the ligam, femoro-tibiale 
internum. 
II. Lateral part. 
a. With a slender but distinct tendon from the intercondyloid 
region and from the outer margin of the femur; its belly 
Proc. Zoou. Soc.—1!882, No. XXII. 22 
