696 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



Genus STREPTOPROCNE Oberholser. 



Streptoprocne « Oberholser, Proc. Biol. Soc. Wash., xix, May 1, 1906, 69, in text. 

 (Type, Hirimdo zonaris Shaw.) 



Very large Cliseturine Swifts (wing 180-235 mm.) with the hallux 

 more than half as long as inner toe, tarsus longer than middle toe 

 with claw, lateral toes scarcely shorter than middle toe, shafts of 

 rectrices very rigid and more or less produced termmally, the colora- 

 tion plain blackish or sooty with a white collar, at least across 

 hindneck. 



Nostrils elliptical, nearly parallel, for the greater part (some- 

 times wholly) anterior to the latero-frontal antia; distance from 

 tips of longest secondaries to that of longest primary a little less than 

 two-thu'ds the total length of wing; tenth (ovitermost) primary 

 longest; tail about one- third as long as wing, emargiriate (S. zonaris) 

 or truncate (5^. semicoUaris) , the rectrices firm, with very rigid and 

 more or less extruded shafts; tarsus longer than middle toe with 

 claw; middle and outer toes equal in length, the inner toe very 

 slightly shorter; hallux (without claw) more than half as long as 

 mner toe (without claw).'' 



Coloration. — Plain blackish or sooty, the adults with a white 

 collar, at least across hindneck. 



« From arpsTzzoc, torquis, and -poKvrj, Progne. (Oberholser.) 



b A peculiarity in the myology of Streptoprocne is thus described by Dr. F. A. Lucas 

 in The Auk, xvi, 1899, 97: 



It might be supposed that the anatomical possibilities of so small a group as the 

 Swifts had been exhausted, but that this is not the case is shown by an examination 

 of Ilemiprocne zonaris, for which I am indebted to Mr. C. B. Taylor, of Jamaica. The 

 cranium is typically cypseline, so are the wing muscles, although the deltoid is small, 

 as in the majority of the true Swifts, there being an apparent tendency to reduction 

 in the number of wing muscles in birds which fly, so to speak, by main strength and 

 in which the humerus is reduced in length. The leg muscles are curious first by the 

 absence of the peroneus longus, a muscle which runs from the head of the tibia to 

 the upper end of the tarsus in Passeres, and second by the great simplification of the 

 deep plantar tendons. In the Passeres, as we all know, one tendon flexes the first 

 digit of the foot, while another with three branches flexes the three front toes. In 

 the Tree Swifts, Macropterygidse, the tendon of the hind toe is attached by a short 

 slip to the branch running to the fourth digit. In the other Swifts so far examined 

 the two main tendons are completely fused for some distance although worked by two 

 muscles. Now in Hemiprocne [i. e., Streptoprocne] while the muscle which ordinarily 

 works the front toes, the flexor perforans, is present, it has no separate tendon, but is 

 attached to the muscle of the first digit, flexor longus hallucis, and is diverted to the 

 work of pulling on its tendon, which as usual runs up over the outer side of the belly 

 of the muscle. Below this single tendon sends off four slips, one to each digit, thus 

 presenting the simplest condition possible and literally realizing Gadow's statement 

 that the flexor longus hallucis is really a common flexor of all digits. If a good generic 

 character is needed for Hemiproaie [Streptoprocne], here it is. 



