I CO LicAS, Characters of the Macropterygidce. lApril 



the name Deiidrochelidon was preoccupied, but since the proper 

 generic name of the Tree Swifts is Alacropteryx, the family name 

 should be Macropterygidce. By the courtesy of Dr. Sclater I have 

 been able to examine an alcoholic specimen of Macropteryx coro- 

 nata, and can now add three important differential characters to 

 those already given. These are as follows : — • 



Mic rop didcB. Ma cropte rygid(E. 



Hj'potarsus simply grooved with one tendinal foramen. 



Shoulder-muscles strictly Cypseline Passerine. 



Deep plantars strictly Cypseline characteristic. 



The accompanying figures bring out these points more clearly 

 than any descriptions and show some other points of interest as 

 well. The plantars of Macropteryx differ from those of the other 

 Swifts in being almost free from one another, curiously enough 

 very nearly resembling those of Apteryx. The extent of their 

 anastomosis resembles that of the Trochilids, but in Macropteryx 

 the flexor longus hallucis is connected with that branch of the 

 flexor perforans digitorum which runs to the fourth digit, while in 

 the Hummingbirds it is connected with the branch to the second 

 digit, much as in the Falconidae. The modifications of the 

 hypotarsus among the Swifts show that the farther a species 

 departs from the typical Cypseline form the more sharply are the 

 tendons differentiated from each other. Thus while all the 

 plantar tendons of Micropus play in a common groove, in 

 Cypseloides and Chcetura they are separated by little ridges of 

 bone, and finally, in Macropteryx the flexor perforans digitorum is 

 honored with a special foramen, just as among the Humming- 

 birds. 



The subject of tendinal individuality and tarsal perforations is 

 extremely interesting, and some day I hope to publish some of 

 the results I am slowly gathering in. These seem to indicate 

 that for morphological characters we must look to the upper end 

 of the tarsus, the distal extremity being particularly subject to 

 physiological adaptations. 



The tongue and alimentary canal of all Swifts examined agree 

 with one another in their general characters, and the tongue is 

 very much as it is found among the Swallows, or even in such a 



