teroventrally between successive thoracic ribs and between the last
cervical and first thoracic ribs.

~_Mm. intercostales internus_~, Fig. 7. These muscles extend
anteroventrally between the last three thoracic ribs.

~_Costopulmonary muscles_~, Fig. 7. This series of muscle slips from the
thoracic ribs attaches to the aponeurosis covering the lungs.

Angiology

Figs. 5, 6, and 7 show all arteries discussed for this family. The
numbers following names or descriptions of arteries in the text refer to
numbered arteries in one of these figures. Insofar as possible, the
numbers used for these arteries are the same numbers used for the
homologous vessels in swallows.

The right and left innominate arteries arise from the aortic trunk and
give rise to the common carotid (14) and subclavian (1) arteries. The
latter continues across the thoracic cavity, giving rise to the coracoid
(2) and axillary (10) arteries, and becoming the pectoral trunk. That
trunk swings posteriorly and leaves the thoracic cavity near the apex of
the costal process, as shown in Fig. 7. Where the trunk passes under _M.
sternocoracoideus_, the thoracic artery (3) is given off.

The various branches of the coracoid artery, again referred to as a
"coracoid complex," are as follows: The first branch, from the posterior
face of the coracoid artery, is a relatively large vessel (6) here
termed the sternal artery; it passes mediad across _M.
sternocoracoideus_, sending off a branch (6a) to that muscle. The right
sternal artery continues posteriorly on the mid-line of the inner
surface of the sternum, and appears to send branches into the various
pneumatic foramina of the sternum, but these vessels are minute and
exceedingly difficult to trace accurately. The corresponding left vessel
is smaller and ramifies on the anteromedial surface of the sternum.
Variations found in these vessels were the following: In one specimen of
_S. inca_ the sternal artery had, on both sides, an independent origin
from the subclavian, lateral to the origin of the coracoid artery. In
_Zenaidura macroura_ both right and left sternal arteries were similar
to the left vessel described above, no median longitudinal vessel being
seen. In _Columba livia_ no vessel corresponding to the sternal artery
was seen. In _Zenaida asiatica_ these arteries penetrated _M.
sternocoracoideus_; no branch to the sternum was seen.

A small complex of vessels (4 and 4a) arises from the lateral face