. Report of the geological exploration of the fortieth parallel . rved in specimen It is hero broadest just below the middle, where the upperedge becomes thin, and somewhat expanded Beyond the middle, tliebone tapers to near the distal end, and the extremity is rounded. Thescapula decreases pretty regularly in thickness from near the proximal tothe distal extremity, where it becomes thin and blade-like. The following measurements indicate the size of the scai)ula inIchthyornis and Apatornis. SHOULDER-GIRDLE OF ICIITIIYORNIS. 143 Measurements of Scapula. {JclUhyomia dispar. No. 171
. Report of the geological exploration of the fortieth parallel . rved in specimen It is hero broadest just below the middle, where the upperedge becomes thin, and somewhat expanded Beyond the middle, tliebone tapers to near the distal end, and the extremity is rounded. Thescapula decreases pretty regularly in thickness from near the proximal tothe distal extremity, where it becomes thin and blade-like. The following measurements indicate the size of the scai)ula inIchthyornis and Apatornis. SHOULDER-GIRDLE OF ICIITIIYORNIS. 143 Measurements of Scapula. {JclUhyomia dispar. No. 1719.) Greatest diameter, across litiiiural articulation, Least diameter, tliroujjli huineral articulation. Length of acromial process, from base, - - Measurements of Scapula, {Ichthyomis victor. No. 1452.) Greatest diameter, across humeral articulation, 8. Least diameter, throus;h humeral articulation, 3. Length of acromial process, from base, - 0-8 The various bones in the scapular arch of Ichthjomis are shown inposition in the figure below. FiO. FiocbeSI.—.capular arch of/f^ttyomij Victor, Marsh; twiro nntnral size. s. scapula; c. coracoid; et clavicle,$L etemum; k. keel of Eternum; «r. ooatal border; g. glenoid fosaa. mm 144 ODONTORNITHES. Measurements of Scapula. {Apatornia celer, Xo. 1734.) Left. Right, Length of scapula, Greatest illaiiieter, across humeral articulation, ° Least diameter, tlirough humeral articulation, 2. Length of acromial process, from base, Diameter of shaft, above humeral articulation, 3. 3. The Coeacoid. (Plate XXIII and XXIX.) In the genus Ichthyornis, the coracoid is a strong bone, much -widenedat the proximal end, where it articulates with the sternum in an elongatedgroove on each side. These grooves, and consequently the coracoids intheir natural position, cross the median line in front in such a mannerthat the right coracoid is external to, or in front of, the left, as in theherons and their allies, and in some oth
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