504- Pi'oceedi)igs of the Royal Irish Academy. 
the chimpanzee and was attached as usual ; there was no ulnaris quinti 
either in the gorilla or in the second chimpanzee. 
The extensor ossis metacarpi pollicis had a double tendon to the 
trapezium and metacarpal bone, as in the chimpanzee ; there was no 
extensor of the first phalanx, and that of the second was one-third 
the size of the first named extensor, in the chimpanzee only one-half. 
— The extensor indicis went to the index finger alone, not to the in- 
dex and middle, as in the chimpanzees. 
The thenar muscles were attached as in man (Plate XXIX., Fig. 3) ; 
the abductor pollicis two-headed; opponens, abductor and the two- 
headed flexor brevis were quite normal. There was an abductor minimi 
digiti from the pisiform, an opponens from the unciform and a flexor 
brevis from the same bone. The four lumbricales were radial, as in 
man, and the palmar interossei were one-headed, adductors forthe index, 
annularis and minimus, together with an extra abductor for the me- 
dius. The dorsals were two-headed abductors for the index, medius 
(radialis), medius (ulnaris), and annularis. 
The muscles of the hind limb were ; psoas parvus very small, but 
present as in the chimpanzees. The psoas magnus and iliacus were 
inseparable, as in the chimpanzees, and were ten times the former in 
size, very nearly equal in the two species ; it extends as high as the 
fourth lumbar vertebra. The quadratus lumborum is also normal. 
The gluteus maximus in the gorilla is large, somewhat trapezoidal, 
separate from the tensor vaginae femoris and equals in weight the 
gluteus medius and pyriformis, instead of making fth of these only, 
as in the chimpanzee. This muscle is, like all the other muscles of 
the leg, absolutely much heavier in the gorilla than in the chim- 
panzee, and has a shorter femoral insertion. The gluteus minimus is 
mainly marginal, and {ththe size of either maximus, or medius, whereas 
it is ^th of the medius in one, and twice its weight in the other 
chimpanzee and f th of maximus in both. The pyriformis was insepa- 
rable in both the gorilla"^' and one chimpanzee, separate in the other. 
The tensor vaginae femoris was one-sixth of the gluteus maximus in 
weight, and quite separate, whereas in the chimpanzee not only was it 
united, but it was only about y o"th- of the maximus. The scansorius 
was united to the gluteus medius, and weighed with it. So it was in 
one chimpanzee, but in the other it was attached to the gluteus 
minimus, and in none was it an absolutely independent muscle. 
There is an obturator externus, and an internus with two gemelli ; 
these are equal in the gorilla, and nearly so in the chimpanzee. The 
quadratus femoris equals frd of the obturator externus, whereas it is 
one-half in the chimpanzees. 
The abductor primus, or condyloid adductor, is large and distinct ; 
the adductors magnus and brevis are fused together; the adductor 
* It was very rotten in our gorilla, and may have been separate when fresh. 
