williston: Kansas pterodactyls. 7 



expansion than is found in Ptcranodon ; its shaft is more rounded and 

 less rugose, lacking especially the strong muscular markings upon the 

 external surface. The articular surface does not appear to differ 

 materially from that in Pteraiiodon. The scapula is of nearly the 

 same length as the coracoid, but is much less stout. It is a thin, 

 spatulate bone, slightly expanded at the distal extremity, where the 

 margin is rounded, and without the characteristic oblique articular 

 facet. It has no supra-glenoid expansion or process on the posterior 

 proximal border, but has its margin nearly straight or gently concave 

 from the articulation to its extremity. The space included between 

 the bones of the two sides as they lie is a nearly regular, oval one, 

 measuring ninety-five millimeters in its greater, forty-five in its lesser 

 diameter. 



The sternum lies at a little distance from the coraco-scapulae. It 

 is an extremely thin bone, with a stout anterior, styliform projection, 

 at the base of which, on either side, looking upward and outward, is 

 the articular, trochlea-like surface for the sternal end of the coracoid. 

 The width between these articular surfaces measures fifteen milli- 

 meters; the length of the process in front of the articulations is 

 twenty-five millimeters. Immediately posterior to the articular sur- 

 faces, the bone expands nearly at right angles to the longitudinal axis 

 to a width of about sixty millimeters. The thin lateral margins 

 are nearly parallel with the longitudinal axis, and show three shallow 

 emarginations between the four costal articular projections. The 

 hind angles are nearly rectangular. The bone, as preserved, is only 

 shallowly concave, and shows no true keel, though a more pro- 

 nounced median convexity towards the front doubtless subserved the 

 function of a carina in part. 



The left humerus lies in position, and is especially characterized by 

 its enormous deltoid crest (radial crest of Marsh), thougli otherwise 

 slender. This crest is. further removed from the head of the bone than 

 is the case in species of Ptcraiiodoii. It is directed somewhat down- 

 ward, and has its distal, gently convex, border about twenty-five 

 millimeters in extent, while the width of the process midway between 

 the extremity and the base measures but sixteen millimeters. The 

 bicipital crest is also prominent. The bone is relatively shorter than 

 in Ptcranodon. 



The humerus, as will be seen from the above description, and from 

 the measurements given below, is remarkably like the same bone in 

 Ptcranodon nanus, as described by Marsh (/. c. supra), and but a little 

 larger. In /-". nanus, however, the coracoid and scapula are said to 

 be firmly co-ossified, and the scapula has of course a different 

 structure. 



