A

Undersurface of atlas with bifid transverse process

B

Left half of atlas seen from the front, showing a growth of bone springing from the upper surface of the transverse process and passing toward the jugular process of the occipital bone

C

Atlas from above showing: a, spicule of bone springing from posterior arch at the upper surface of the point of junction of lamina and pedicle and passing over the position of nerve and artery to the back part of the superior articular surface; b, a second spicule of bone passing from upper surface of transverse process to the outer edge of the superior articular surface and crossing the place of exit of the anterior division of the first spinal nerve. A probe, c, is represented passing through the abnormal foramina.

D

The same atlas seen from the front, showing the foramen which looks forward and gives passage to the anterior division of the first spinal nerve.

E

Occiput and atlas fused together, posterior view; the abnormal pillar described in (Allen's) text is shown; also the atlas and base of skull are seen to be further separated on that side

F

Shows a large anterior and posterior tubercle

G

Shows an imperfect posterior arch, also a suture i nthe middle of the anterior arch, and on the left side a deficiency of the anterior root of the transverse process

H

Atlas with posterior arch open and transverse process thrown forward, probably from the cause suggested in (Allen's) text

I

Semidiagrammatic view of the abnormal atlas described, in which the posterior arch is absent and the anterior is in two parts

J-L

These figures represent the left halves of a normal atlas, axis, and typical cervical vertebrae; the same letters in each point to the homologous parts:a represents the position of the point in each which corresponds to the tip of a rib, bto the rib tubercle, and cto the tip of the transverse process proper