SKELETON OF BIMANA. 581 



wliich liave an articular facet playing upon a joint, are the 

 *• patella,' fig. 183, 66^, the pair beneath the metatarso-phalangial 

 joint of the great toe, and the pair at the corresponding part of 

 the thumb. Of those playing on surfaces of bone, there is one in 

 the tendon of the peroneus longus which glides on the groove of 



40-2 



Sections of A femur, B tibia, and fibula. 



the cuboid ; one in the tendon of the tibialis anticus opposite the 

 smooth facet on the entocuneiform ; one in the tendon of the 

 tibialis posticus opposite the inner side of the astragalus; and 

 one (fabella) in the outer head of the gastrocnemius behind the 

 outer condyle of the femur. The os penis, common in Quadru- 

 mana, is never developed in Man. 



D. Relations to Archetype. — Finally, in regard to the skeleton 

 of Bimaiia, there remain a few observations on its relations to the 

 general vertebrate archetype (vol. i. fig. 21), from which it de- 

 parts so widely. 



The skull shows the following extreme modifications. In the 

 occipital segment the hajmal arch is detached and displaced, as in 

 all Vertebrates above fish ; its pleurapophysis (scapula, fig. 403, 

 pi, 5i) has exchanged the long and slender for the broad and fiat 

 form ; the h^mapophysis (coracoid, o2) is rudimental, and coalesces 

 Avith 51 : the diverging appendage, 53-57, of this arch becomes the 

 ' pectoral limb.' The nenrapophyses (exoccipitals, 2) coalesce with 



