366 MR. J. BESWICK PERRIN ON THE 
as already mentioned, a tendon from the soleus series. The tendons are distributed 
respectively to the bases of the distal phalanges of the Ist, 2nd, 3rd, and 4th digits 
(that to the 3rd digit being the largest). The tendon to the 1st digit presents a remark- 
able arrangement. It passes through a cleft between the Ist and 2nd metatarsal bones 
to attain the flexor aspect of the hallux, grooving the trochlea of the metatarsal phalan- 
geal articulation. On the under surface of the tendon of this muscle is a lumbrical 
muscle which springs solely from it. It is inserted into the proximal phalanges of the 
2nd and 3rd digits. 
Besides these muscles there are an extensor and flexor brevis hallucis, and a flexor 
brevis and abductor minimi digiti. These muscles present no remarkable peculiarities 
in their attachments. The same may be said of the cephalic, cervical, and abdominal 
muscles’. 
The muscles of birds present considerable uniformity in disposition, more so than their 
multitudinous differences in external configuration and diverse habits would lead us to 
infer. What tendency there is to muscle-change culminates in a great measure into a 
difference in degree of development. In a bird that cannot fly, the muscles of the wing 
are of an impoverished kind ; in birds which use their wings the muscle are large and 
substantial; and intermediate between modified and abundantly developed muscle-tissue 
there are many shades of difference. 
However interesting muscular anatomy may be, as applied to birds only, it is of a 
secondary character to the broader view which must be considered—namely, general 
morphology. Every one in the habit of dissecting animals and comparing one with 
another cannot fail to be impressed with the wonderful adhesion manifested to one type 
or plan. There is more or less absolutely a general similarity, with minor illustrative 
differences, the latter indicating evolution, but not by any great and untraceable strides, 
but by an easy gradation, which seems to continue uninterruptedly irrespective of 
function. There is one fact—and a significant fact it is—that muscles are met with in 
birds, which are of not the slightest use, just as we meet with them in animals higher in 
the scale. But these muscles are as important to the morphologist as the ruins of 
ancient cities, old castles, and other time-shattered remnants of architectural design and 
skill are to the archeologist. The former are illustrative ruins of natural structures, as 
the latter of artificial ones. It must not be inferred that function, circumstantial con- 
ditions and other operative agents do not play a prominent part in muscle-evolution ; 
there can be no doubt that they do; but these are the lesser lights which disport them- 
selves round the adapting master power. 
In the Opisthocomus the muscles of both upper and lower extremities are remarkably 
well developed, especially those of the latter. 
1 T am sorry that a combination of circumstances has prevented me consulting the extensive bibliography 
which exists on Avian myology. Ihave simply described what I found, and named the muscles as nearly in _ 
accordance with their analogues in the higher animals as I possibly could. 
