from Middle Eocene, Wyoming. 55 



subequal, about two-thirds as long as the middle one, and hallux 

 one-third as long ; middle digit and tarso-metatarsus of equal length. 

 Plumage unknown. 



The general appearance of this specimen is shown in the 

 accompanying Plate, which is repi'oduced from a photograph with- 

 out retouching. It will be seen that the body lies with its right 

 side embedded in the matrix, the right hind-limb in advance of the 

 left, the humeri elevated and overlying a bend in the neck. The 

 right fore-wing is wanting, and the left is doubled over so as to 

 expose the humerus from the palmar and the remaining wing-bones 

 from the opposite or ventral aspect. The pelvis also is seen from 

 the ventral side, the right hind-limb from in front, and the left 

 partly from in front, partly from one side. Thus, one of the 

 femora presents a lateral and the other an anterior view, but the 

 coracoids and scapulas are so turned as to exhibit mutually corre- 

 sponding sides. 



To speak of the imperfections first, the ribs are broken and 

 confused, the caudal vertebrae are wanting, the dorsal displaced 

 and in part scraped away by careless use of tools in the hands 

 of a collector, and the cervicals in part concealed by the humeri. 

 Between tlie scapulce, and between the humeri and occiput, the 

 vertebral column appears largely in section, owing to unfortunate 

 mutilation. Most serious of all, however, is the damage done to 

 the head, the bone-substance being so cut into or scraped away 

 as to make it impossible to distinguish the separate elements. 

 Depredations of this nature are wholly inexcusable, and cannot be 

 too severely censured. 



The sternum is well shown in lateral aspect, its body, however, 

 being much compressed. The latter gives off a very long and 

 slender intermediate xiphoid process, and a stouter and shorter 

 external xiphoid, the distal extremities of both being expanded. 

 The costal condyles for articulation with the sternal ribs are very 

 small, and the costal process of only moderate proportions. There 

 is a well-developed rostrum or manubrium, and the coracoid grooves 

 are broad and deep. The coracoids themselves are relatively short 

 and stout, without subclavicular processes and foramina ; their 

 sternal facets are considerably arched, and there is a faint hyosternal 

 process. The clavicles form a narrow V-shaped arch, implying 

 reduced powers of flight. The scapula? are long and slender, with 

 well-developed glenoidal and acromial processes, and are not distally 

 expanded. 



The bones of the fore-Umh do not require special comment. The 

 right humerus is seen in radial aspect, and shows a broad delto- 

 pectoral crest and prominent distal condyles. The latter are 

 especially well displayed in the palmar view presented by the left 

 humerus. Eflfects of pressure are apparent in the extreme width of 

 the remaining wing-bones. It is possible, in addition, that the 

 ulnse of both wings are superimposed or are crushed contiguous to 

 one another. Since the photograph was taken, all the limb-joints 

 have been more fully exposed with the point of a needle. 



