STUDIES OE THE MACROCIIIRES. 



353 



very closely to some Cuciilincd, namely the Cypseli. For this 

 reason I usually place it at the end of the PasserinaB, in the 

 vicinity of the anomalous cuculine form just mentioned, which 

 stands in the same relation to the true Cuckoos as the Swallows 

 to the ordinary Song-birds. However, pterylographically, Hi- 

 rundo does not differ from tlio rest, but rather harmonizes com- 

 pletely with Dicceum, in that the rows of single contour-feathers 

 uniting the saddle with the rump-band are either entirely deficient 

 {H. rustica^ H. urlica) or indicated only by two rows of very sparse 

 contour-feathers {H. riipestris). The dilatation of the pectoral 

 part of the inferior tract is somewhat divergent at the end. The 

 number of remiges is eighteen, of which nine are on the hand, 

 and of these the first is the longest ; the first six secondaries are 

 remarkable on account of their broad, emarginate extremities " 

 (pp. 84, 85, ' Pterylography '). 



Now, in Frogne I note that the " saddle " at the end of the 

 spinal tract is very broad, although forked as in Sirundo nrhica, 

 but the posterior extremities of the limbs of this bifurcation are 

 joined, on either side, to the anterior end of the rump-tract by 

 distinct and well-marked rows of contour-feathers. Further, the 

 bifurcation of the " saddle " takes place at about the middle of 

 the back, and not nearly so low down, namely betw^een the thighs, 

 as in Sirundo. Another point to note upon this dorsal aspect 

 in Frogne is that the "alar tracts" are very extensively joined 

 with the anterior endings of the " humeral tracts." In Hiriindo 

 Nitzsch even seems to leave an unfeathered space, on either side, 

 in these localities. The " capital area " is the same, but in 

 Frogne there are no naked areas around the eye and auricular 

 orifice, as in Cypselus, and as Nitzsch has also drawn them for 

 H. urbica. 



Under the throat in Frogne and in most Swallows we find a 

 longitudinal naked strip running down close to and just within 

 the ramus of the mandible, on either side, which terminates at 

 about the angle of the jaw. It will be remembered that in the 

 Whip-poor-wills and others this feature is also present, except 

 in them it assumes a somewhat difierent type, the feathers of the 

 throat being arranged in regular rows. I am inclined to believe 

 that there is a reason for this, which is, that in these birds, accus- 

 tomed as they are sometimes to swallow very large insects, an 

 operation which must distend the throat, or even momentarily 



