Macalister — On the Muscular Anatomy of the Gorilla. 505 
longus is small and separate, and the pectineus only one-half of the 
last ; the whole adductor group of muscles is to the gluteal series as 
95 to 100, while in the chimpanzee they are as 86 to 100. The 
sartorius was normal in all. 
The hiceps had a perfectly separate femoral head, which was half 
the weight of the ischiatic ; it was much larger in the chimpanzees. 
The semi-tendinosus had its usual inscription, and exceeded the biceps 
ischiaticus in size. The semi-membranosus was equal to the femoral 
biceps in size, thus the inner hamstrings were to the outer as 16 is to 
15. The quadriceps extensor differed in no respect from that in man? 
its rectus element was distinct and two-headed, and formed \ih. of the 
mass; the extensors were to the flexors as 100 to 70, while in one 
chimpanzee they were as 100 to 56 : if we add to these the gracilis, 
which functionally acts as a flexor, it materially alters the proportion, 
making it in the gorilla, extensors : flexors : : 100 : 97, that is, prac- 
tical equality, and in the chimpanzee, ex. : fl : : 100 : 80. 
The popliteus muscle had a sesamoid bone or cartilage ; it was about 
as large proportionally as in man. The two heads of the gastrocnemius 
were inseparable, the internal being a little the larger ; in the chim- 
panzee they are much more separate. The plantaris was absent on 
both sides, both in the gorilla and one chimpanzee ; it was present on 
the right side of the other, and absent on the left. The soleus was 
larger than the gastrocnemius (31 : 29) while it was smaller (14 : 17) 
in the chimpanzee ; on the right side there was a trace of a tibial 
head. 
The flexor digitorum longus was -36, the size of the flexor hallucis; 
and on separating the united tendons of these muscles in the foot, the 
fibres of the flexor digitorum were traceable to the 2nd, 3rd, 4th, and 
5th digits, while those of the fle:S:or hallucis went to the 1st, 2nd, 3rd, 
and 4th. In the chimpanzee the flexor digitorum is one-half the size 
of the flexor hallucis, and it supplies the 2nd, 3rd, and 5th digits, while 
the flexor hallucis supplied the first, third, and fourth. 
The tibialis posticus was a strong muscle, inserted as usual into 
the scaphoid and ento- cuneiform, but it sent a slip to the head of the 
third metatarsal bone. This I did not find in the chimpanzee. The 
flexor digitorum brevis was strong, and sent no slip to the little toe ; the 
accessorius was small and oblique. The tibialis anticus was double, 
one half going to the ento-cuneiform, the other, which was only jth the 
size, was inserted into the metatarsal bone of the hallux. In the chim- 
panzee it is the same. 
The extensor hallucis proprius is a distinct oblique muscle, much 
larger than the corresponding muscle in the chimpanzee, and arising as 
usual from the middle of the fibula. Extensor digitorum longus is not 
much stronger, and sends off four tendons to the outer toes ; the fiexors 
of the toes are to the extensors as 3 : 1 . In the chimpanzee they are 
in the same proportion. The peroneus longus is weaker than the 
brevis (double it in the chimpanzee) ; the peroneus quinti exists as a 
tendon in both ; there is no peroneus tertius. 
