MBIDAE

Figs. 5, 6, and 7 illustrate the following muscles and arteries
described for _Scardafella inca_.

Myology

~_M. pectoralis thoracica~_, Fig. 5. The origin is from approximately the
ventral third of the keel, the lateral and anterior portion of the
clavicle and the adjacent sterno-coraco-clavicular membrane, and from
the lateral portion of the sternum and the fascia overlying the thoracic
ribs. This massive muscle covers the entire ventral surface of the
thorax, converges, and inserts on the pectoral surface on the ventral
side of the humerus.

~_M. supracoracoideus~_, Fig. 5. The origin is from the dorsal two-thirds
of the keel and medial half of the sternum (where the origin is bordered
ventrally, posteriorly, and laterally by the origin of _M. pectoralis
thoracica_) and from the sterno-coraco-clavicular membrane adjacent to
the coracoid. This large pinnate muscle converges, passes through the
foramen triosseum, and inserts by means of a strong tendon on the dorsal
surface of the humerus on the deltoid ridge.

~_M. coracobrachialis posterior_~, Fig. 5. The origin is from a prominent
lateral wing on the posterolateral portion of the coracoid, and from the
lateral surface of the proximal two-thirds of the coracoid. The
insertion is by means of a tendon on the internal tuberosity of the
humerus. Of the muscles described here, this one differs most strikingly
from the homologous muscle in _P. subis_. The difference can be seen by
comparing Figs. 1 and 5.

~_M. sternocoracoideus_~, Figs. 5, 6, and 7. The origin is from the
external, and to a slight extent from the internal, surface of the
costal process. The insertion is on a posterolateral triangular area on
the dorsal surface of the coracoid.

~_M. costi-sternalis_~, Figs. 5 and 6. The origin is from the anterior
edge of the sternal portion of the first three thoracic ribs. The muscle
converges and inserts on the apex of the costal process.

~_M. subcoracoideus_~ (ventral head), Fig. 6. The origin is from the
manubrium and from approximately the posterior half of the coracoid and
on the medial and dorsal surface of that bone, and the medial side of
the sterno-coraco-clavicular membrane adjacent to the coracoid. The
ventral head passes anterodorsally to join with the dorsal head (not
here described), and the combined muscle inserts by a tendon on the
internal tuberosity of the humerus.

~_Mm. intercostales externus_~, Fig. 5. These muscles extend
pos