ANATOMY OF THE LEMUROIDEA. 99 
abnormality in Man. Only in scattered genera of the lower Mammals is the union 
found; but where it does exist it is large, and powerfully aids the combined actions 
of the superficial and deep flexors. 
The multiple origin of the three muscles in question (flex. sublimis, profundus, and 
longus pollicis) is curious and interesting homologically as regards family relationship, 
and also as regards the serial homology between flexors of palm and sole. In the 
higher Quadrumana the tendons of the flexor profundus and pollicis more com- 
monly, but not always, pass in separate slips below the annular ligament, the former 
muscle usually supplying the second, third, fourth, and fifth digits, the latter the 
pollex. Variations take place wherein the pollicial tendon splits and partly goes to the 
index, or where union takes place between the common deep flexor and longus pollicis, 
the latter even appearing as but a slender tendon from the former. These so-called 
variations culminate in the Lemuroids, and even reverse the primordial relationship of 
the muscles and tendons, inasmuch as the flexor longus pollicis encroaches considerably 
on the domain of the profundus, becomes far the larger muscle of the two, and in 
Nycticebus sends on the main tendons to the first, second, third, and fourth digits. The 
palmar tendinous type of the group diverges into two, one wherein the flexor profundus 
and pollicis unite as a broad flat tendon, ending in five equal or subequal digital seg- 
ments: the genera Lemur, Galago, Perodicticus, Tarsius, and Cheiromys fall under this ; 
the second, as witnessed in the Slow and Slender Loris, has separate proximal palmar 
tendons, the flexor longus pollicis becoming functionally the more important, and, as 
already said, acting as the tendinous lever of three or four of the radial digits, whilst 
the flexor profundus digitorum lessens its tendons to the fifth and fourth or only fifth 
digit, branchlets merely uniting it with the enlarged flexor longus pollicis tendons. 
These examples of differentiation are highly important as affording proof of the identity 
of the muscular relations of the hand and foot; for the flexor longus hallucis supplants, 
in great part, the flexor longus digitorum both in size of fleshy belly and tendinous 
insertion. The increase of force resulting from the palmar union is shown prominently 
in those lower Mammals where the manus serves the office of a scratching or digging 
apparatus, notably so in Talpa. It may be a question whether this change of tendinous 
type is not as much due to the uses and modes of life of the animals thus identically 
distinguished as purely to family organization. As regards the interossei, these manifest 
higher character in a slight exhibition of dorsal ones, but on the whole they more closely 
exemplify lower forms in being true flexores breves of the palm and sole. The extra 
superficial layers are of common occurrence, and indeed almost the rule, in inferior 
families. 
In the arrangement and relative size of the psoas parvus magnus and iliacus the 
Lemuroids more resemble the Squirrel, Kangaroo, Seal, &c. than most Apes; this may 
follow as a consequence from the great extent of the lumbar region and similarity of 
some of these in habits, and is certainly no evidence of any affinity. 
