114 ORGANS OF SUPPORT, 



moveable patella at the elbow, like that of the knee-joint. 

 The carpal bones occupy a very small space in the hand, and 

 the long fingers are here fixed in a state of extension, as they 

 are in the hand of the bird, the thumb alone admitting of free 

 flexion and extension. The hand of the bats rotates on the 

 carpal end of the radius by a motion of abduction and adduc- 

 tion, as the wing of the bird, so that, when folded, the little 

 finger lies along the outside of the radius. The thumb is not 

 enclosed in the interdigital membrane, but is extended for- 

 wards free as a prehensile organ for progressive motion, or 

 for suspending its body. The long slender meta-carpal 

 bones and phalanges of the four succeeding fingers support 

 the interdigital membrane, and there are often claws on the 

 fore and on the middle finger. The small legs are twisted 

 outwards from their commencement in the oblique cotyloid 

 cavities of the open pelvis. The femur is of a cylindrical 

 form, slender, and with a large articular head, and a large 

 trochanter minor directed forwards, the trochanter major 

 being here turned backwards. The fibula is broad at its 

 tarsal extremity, but is almost lost before it reaches the 

 upper end of the long slender tibia. From the retroverted 

 direction of the cotyloid cavities and of the whole legs the 

 tibia is" placed externally, and the fibula internally. The 

 short bent calcaneum directed inwards has often extending 

 from its tuberosity, along the margin of the interfemoral 

 membrane, a slender elastic bone, which supports that 

 membrane. The slender parallel toes directed backwards 

 terminate in long, curved, sharp prehensile claws, by which 

 they most frequently suspend their body in an inverted posi- 

 tion, the best suited for their launching instantaneously into 

 the air with outspread wings, when called by hunger or 

 alarm. 



In the lowest of the quadrumanous animals, as the lemurs 

 of Madagascar, the jaws are still lengthened for numerous 

 insectivorous molar teeth, and the skeleton generally is 

 adapted for the horizontal position of the trunk. The oc- 

 cipital foramen is placed near the posterior margin of the 

 skull, the mastoid cells are as large as in carnivorous quad- 

 rupeds, and although the orbit is here surrounded with an 

 osseous margin, it is still continuous behind with the tem- 

 poral fossa. The cranial cavity, however, is here capacious, 



