Chapter M

Extreme length of scapula ·42
Extreme length of spine ·31
Extreme thickness of spine at upper margin ·098
Extreme height of spine ·109
Basal width of proximal end of spine ·032
Basal width of distal end of spine ·030
Basal width of middle part of spine ·011
Length of glenoid cavity ·149
Width of glenoid cavity ·096

_The Humerus_ (Plate VII., Fig. 1).--The humerus is short, but excessively stout, twisted slightly on its axis; it decreases gradually in size downward, with the smallest diameter about two inches below the end of the deltoid ridge. The head is large, hemispherical, and sessile, projecting very slightly out of the axis of its shaft. The great tuberosity is heavy, but not high, and is separated from the low lesser tuberosity by a shallow bicipital groove.

The trochleæ are very nearly equal in size, directed obliquely to the axis of the shaft, and are separated by a narrow groove, which runs from the supra-trochlear fossa down and in, then back and up to the anconeal fossa. The condylar tuberosities are large and rugose; the external is the greater, and is directed antero-posteriorly. The deltoid ridge is long and heavy, and extends nearly two thirds down the shaft, branching out into two forks near its end. The supinator ridge is short and rudimentary, differing in this respect entirely from the great development found on the humerus of the _Proboscidea_.

The supra-condylar fossa is small, subcircular in form, and very deep, it has the peculiarity of being placed above the external condyle alone. The anconeal fossa is median in position and quite deep.

_Measurements of Humerus._