52 PROCEEDINGS OF THE ACADEMY OF [1897. 



the foot. They uniformly arise more superficially on the plantar 

 surface and in part overlap the others. The more powerful muscles 

 tend to abduct the metatarsi ; the weaker to antagonize these and to 

 adduct the metatarsi. 



Burmeister reverses the proportions of the two sets of muscles. 

 The figure (fig. 11, taf. 5) expressly shows the adducting set and 

 named by him the plantar to be the larger and more superficial. 



NOTES ON THE MECHANISM OF THE LIMBS. 



The superior extremity is small and weak. 12 Flexion of the el- 

 bow is but 10 mm. as measured by the excursus of the head of the 

 ulna. The bones of the forearm do not agree with Burmeister's de- 

 scription, while his figure of the relation of the radius and ulna are 

 again quite different from that in T. fuscus. Instead of a wide inter- 

 osseous space the specimen shows a narrow one, the bones are almost 

 in contact except at the middle third where the interval is but one- 

 half mm. 



The radius moves scarcely at all on the ulna, so that prona- 

 tion and supination are not as marked as would be inferred from 

 the size of the Pronator radii teres and the two supinators. 



The presence of a bold ridge on the outer side of the humerus 

 above the epicondyle answers to the large Supinator longus in alli- 

 ance with the Extensor carpi radialis longior. 



The hand lies at right angles to the forearm by extreme dorsal 

 traction ; the first row of phalanges is semi-flexed, the second row is 

 acutely flexed, while the third row is extended. The thumb is not 

 opposable, but the metacarpal bone is sharply adducted so that the 

 phalanx lies under the index finger. The metacarpo-phalangeal 

 articulation is very loose. 



On p. 49, statements are made to account for the longitudinal grasp 

 of the foot. This position places the Peroneus longus in admirable 

 phase for drawing the tibial margin of the foot in toward the plane 

 of support. The weight of the body bears not only through the 

 astragalus to the astragalo-scaphoid ligament, but the calcaneum is 

 supported on the sling-like Plantaris as well as on the Gastrocnemius 

 and Soleus. 



The amount of strain in the position is indicated by the smooth 

 concave pulley-like surface on the calcaneum, and the insertion of 



12 In a skeleton of Tarsius which I identify as that of T. fuscus in the 

 American Museum of Natural History. New York, the presternum was found 

 to be cartilaginous. 



