54 PROCEEDINGS OF THE ACADEMY OF [1897. 



bones form conspicuous projections into the sole, and thereby define 

 the sides of a depression in which lie the conjoined tendons of the 

 Flexor longns digitorum and the Flexor longus pollicis pedis. 



The ligamentum plantar e longum ol Burmeister is the same as 

 the suspensory ligament. It extends pari passu with the elongation 

 of the scaphoid bone and bears a close resemblance to a tendon of a 

 muscle. It attaches itself to the tibia and the distal end of the sca- 

 phoid bone, some fibres being held to the calcaneum opposite the as- 

 tragalus, others being merged with those forming the posterior liga- 

 ment of the ankle joint. The metatarso-phalangeal articulations are 

 extremely loose and the toes are so disposed as to show tibial deflec- 

 tion, the longer ones overlapping the shorter. The thumb on the 

 other hand shows fibular deflection being drawn toward the palm by 

 powerful muscles. The first row of phalanges is not extended on 

 that of the metatarsus (as the first row of phalanges is extended on 

 that of the metacarpus) but is on the same line. The second to the 

 fifth toes resemble the fingers in motion and position, but the great 

 toe remains extended. 



The weakness of the foot support is doubtless harmonized with the 

 extent of the knee flexion. Hence the muscles of the calf practically 

 disappear in the deep recess between the ham strings. The inclination 

 forward of the trunk is checked by the great mass of the Erector 

 spince muscles, with which the deep groove between the dorsal and 

 broad transverse processes of the thoracic and lumbar vertebra? cor- 

 relate. The tail and its muscular power, especially at its base, may 

 be taken as a balance of weight to that of the trunk, the hip joint 

 being accepted as the fulcrum. When the limb is extended the hind 

 feet yield a support too feeble to hold up the body. When the limb 

 is flexed the line of support passes from the foot to the ischium ; 

 even then the trunk inclines forward. This inclination is checked 

 by the ham strings. The " spring " consists in the extension from 

 extreme flexion. Although extension at the knee is greatly re- 

 stricted, the power necessary to the end is expressed in the enormous 

 Vasti. 



According to De Blainville the respective lengths of the calca- 

 neum and scaphoid bone as seen in Tarsius is repeated in Otolienus. 

 Recalling the fact that these forms are now to be placed in different 

 phylla, we recognize that the elongatiou of the two bones is an 

 adaptive character. 



