14 BULLETIN 57, UNITED STATES NATIONAL MUSEUM. 



Among recent mammals the nearest approach to the conditions just 

 described is found in the Colugidae. Here the trochiter and trochin, 

 though less developed than in the Pteropidae, strongly- suggests the 

 form characteristic of the bats as compared with' their much more 

 rudimentary condition in Tupaia. Of the two processes the trochin 

 is distinctly the larger, and it is obvious at a glance that the distal 

 extremity of the humerus in Cynocephalus more nearly resembles 

 that of Pteropus than it does that of Tupaia or than that of Pteropus 

 does the most highly developed type in the Microchiroptera. This 

 resemblance is further heightened by the size and form of the deltoid 

 crest, which is rather closely alike in Cynocephalus and Pteropus, 

 while in both Tupaia and the Microchiroptera it is noticeably dif- 

 ferent. At the distal extremity of the humerus the resemblance be- 

 tween Cynocephalus and the bats is less exclusive. In the Colugidae 

 both supracondylar foramen and supratrochlear perforation are 

 present and the supinator ridge is well developed, characters all of 

 which are in common with the Insectivora. The actual surface of 

 articulation, however, resembles that of the bats in the reduction of 

 the trochlea and the large size of the capitellum, the outer edge 

 of which shows the first suggestion of the groove and ridge which is 

 so prominent a feature in the Chiroptera. As would be expected 

 from the reduced condition of the trochlea, the ulna is much reduced 

 from its normal form. It is throughout very slender, the distal half 

 flattened against radius, into which it blends near wrist. Proximally 

 it is slightly larger than in Pteropus, though very greatly reduced as 

 compared with Tupaia, and the small, abruptly curved olecranon 

 forms a definite part of the joint, its extremity fitting into the supra- 

 trochlear perforation. 



It seems, therefore, that without touching on the question of the 

 general relationships of the Dermoptera, it- may safely be said that 

 the long bones and two principal joints of the anterior limb in this 

 group are intermediate in structure between those of Insectivores and 

 Bats, but distinctly nearer the latter, and that in this respect at least 

 Cynocephalus represents a stage that was passed through by the near 

 ancestors of Pteropus. 



In 1892, Winge " first called attention to the striking differences, 

 already alluded to, in the humerus and shoulder joint of the Mega- 

 chiroptera and of the more highly specialized Microchiroptera. A 

 fact not mentioned by Winge is that, while the Microchiroptera, as a 

 whole, show a much more specialized condition of the humerus than 

 the Megachiroptera, different members of the group show different 

 degrees of this modification, and these degrees are very largely charac- 



<> Jordfundne og Nulevende Flagermus (Chiroptera) fra Lagou Santa, Minas 

 Geraes, Brasilien, p. 24. 



