suffraginis, and inferiorly with the third phalanx and the navicular bone.

[Illustration: FIG. 1.--THE BONES OF THE PHALANX. 1, The os suffraginis; 2,
the os coronæ; 3, the os pedis; 4, the navicular bone, hidden by the wing
of the os pedis, is in articulation in the position indicated by the barbed
line.]

[Illustration: FIG. 2.--SECOND PHALANX OR OS CORONÆ (ANTERIOR VIEW).
1, Anterior surface; 2, superior articulatory surface; 3, inferior
articulatory surface; 4, pits for ligamentous attachment.]

[Illustration: FIG. 3.--SECOND PHALANX OR OS CORONÆ (POSTERIOR VIEW). 1,
Posterior surface; 2, gliding surface for passage of flexor perforans; 3,
lower articulatory surface.]

Cubical in shape, it is flattened from before to behind, and may be
described as possessing six surfaces: _An anterior surface_, covered with
slight imprints; _a posterior surface_, provided above with a transversely
elongated gliding surface for the passage of the flexor perforans; _two
lateral surfaces_, each rough and perforated by foraminæ, and each bearing
on its lower portion a thumb-like imprint for ligamentous attachment, and
for the insertion of the bifid extremity of the perforatus tendon; _a
superior surface_, bearing two shallow articular cavities, separated by an
antero-posterior ridge, for the accommodation of the lower articulating
surface of the first phalanx; _an inferior surface_, also articulatory,
which in shape is obverse to the superior, bearing two unequal condyles,
separated by an ill-defined antero-posterior groove, which surface
articulates with the os pedis and the navicular bone.

_Development_.--The bone usually ossifies from one centre, but often there