The Myology of Chimpanzee and Baboon. 451 
the gastrocnemius to be inserted into the medial border of the 
Tendo Achillis. In comparison with man, this belly is longer. 
The tibia of the chimpanzee is 20 em. long, that of man from 45 
to 50 em. (Gray). In both cases the plantaris is 6 em. long. 
Beddard found this muscle present in the chimpanzee, while 
Champneys did not. Michaélis says it was well developed in 
the baboon but absent in the chimpanzee and orang. It was lack- 
ing in the orang of Primrose. Duckworth says it is never found 
in the gorilla, but frequently in the chimpanzee; it is normal in 
the Cercopithecide and Lemuroides. Hartmann found it in his 
chimpanzee, although he says Bischoff and Brihl at first denied 
its existence. He did not find it in either the gorilla, the orang, 
or the gibbon. Kohlburgge reports its absence in the chimpanzee 
in 43 per cent of cases and Loth in 45.7 per cent. Le Double 
found rather frequent cases of the absence of this muscle in man. 
However, in colored races its absence is rare. The plantaris, 
as well as the palmaris its homologue in the arm, exemplifies a 
degenerating muscle. Wiedersheim (p. 109) states that ‘‘as 
an original flexor (the plantaris) must have begun to degenerate 
from the time the plantar fascia became secondarily attached to 
the calcaneus, and helped in the formation of the foot as the latter 
became transformed into a supporting organ.’ See table III. 
TABLE III 
ANIMAL | REPORTED BY OCCURRENCE OF PLANTARIS 
Chimpanzee Beddard | present 
Chimpanzee | Hartmann present 
Chimpanzee | Champneys absent 
Chimpanzee | Michaélis | absent 
Chimpanzee Duckworth | frequently found 
Chimpanzee Author present 
Chimpanzee Kohlbrugge absent in 43 per cent 
Chimpanzee Loth absent in 45.7 per cent 
Man Le Double frequently absent 
Orang Duvernoy absent 
Orang Michaélis absent 
Orang Hartmann absent 
Orang Primrose absent 
Baboon Michaélis present 
Cercopithecidae Duckworth present 
