Zoological Society. 65 



Tlie extensor brevis digitorum pedis arises from the os calcis, and 

 divides into three portions; the strongest of which gives two ten- 

 dons to the second toe, one being inserted at the base of the proximal 

 phalanx, the other expanding over the second and distal phalanges 

 lil:e the tendons of the extensor longus. The remaining portions go 

 to the fibular aspect of the third and fourth toes. 



The peroneics longus and brevis arise together from the outer, fore, 

 and back part of the Jibula ; on the latter aspect the)' are in con- 

 nection with thejlexor longus poUicis. The tendon of the peroneus 

 brevis is inserted into the base of the metatarsal bone of the little 

 toe. The tendon of the peroneus longus passes under the cuboid 

 bone, without the interposition of a sesamoid bone, crosses the foot, 

 and is implanted into the metatarsal bone of the thumb of the 

 hinder hand, of which, as far as the structure of the articulation 

 will permit, it is ajlexor. There is no peroneus tertius. 



The thumb is very short, consisting, in the female at least, 

 of only two bones, set on at right angles to the foot, and at a 

 great distance from the toes. In this part, however, the power of 

 a considerable muscular apparatus is concentrated. Receiving no 

 tendon from ihe Jlexor longus pollicis, it is rendered more inde- 

 pendent in its actions; not being necessarily flexed, except in the 

 action which turns down that side of the foot to which it is attached, 

 and by which it is brought closer to the object to be seized. On 

 the sole of the foot we find an abductor and an adductor poUicis, both 

 powerful muscles inserted at very open angles into the phalanx ; 

 which, when they cooperate in their contraction, they must draw 

 down in the diagonal with great force. Between these are situated 

 two more direct flexors, constituting what is usually termed the 

 Jlexor brevis poUicis. 



The space between these muscles, which in man and the Chim- 

 panzee is filled by the tendon of the Jlexor longus pollicis, in the 

 Orang Utan is occupied by a small peculiar muscle which arises 

 from the metatarsal bone, and is inserted into the phalanx. In a 

 young male Orang that had two phalariges the flexor brevis was 

 inserted partly into the second phalanx. The extensor brevis pol- 

 licis arises from the os naviculare and os calcis, and is inserted into 

 the base of the proximal phalanx, when there are two. 



On the dorsum of the foot may also be observed interossei ex- 

 lerni of a penniform shape; they are attached to the fibular aspect 

 of the proximal phalatigcs of the toes. There was also an adductor 

 minimi digili, and interossei interni, but not any trace of transver- 

 sulis pedis. 



Mr. Owen concluded his observations with some remarks on the 

 structure of the principal joints of the lower extremity, and on the 

 degrees of mobility of which they are susceptible. 



In the hip-joint the most remarkable circumstance is the freedom 

 of motion in the rotation inwards; this is, however, more limited 

 than in tiie opposite direction. The motions of flexion and ex- 

 tension, abduction and adduction, are also very free. On examining 

 the cause of tlie limitation of the inward rotation, he found it to be 



A^.^V. \'<)l. 10. No. 5.5. Juhj 18:n. K a strong 



