354 



DR. E. W. SHrPELDT's MORPHOLOGICAL 



place the integument tliere on the stretch, these unfeathered 

 strips would spread to meet the action, but as the parts came to 

 rest again after swallowing, the feathered areas or strips would 

 again become juxtaposed and the throat apparently full-feathered. 

 In some Swallows (e. g. Clielidon) these naked strips are only 

 brought fully into view by stretching the integument of the 

 throat. 



No special note is necessary to be taken of the ventral ptery- 

 losis of Progne, as it has all the essential characters of the pattern 

 seen in a Passerine bird, and departs but slightly therefrom. 

 It is more like Cypselus, however, than it is like such a form as 

 AmpeUSf for instance, in that the ventral tract, on either side, 

 overlying the pectoral region, does not show that heavy feather- 

 ing to its external margin as seen in the latter type. In Swal- 

 lows, as in all Passerine birds, the oil-gland is nude. 



Now I have plucked, with the greatest possible care, an adult 

 male specimen of every Swallow in our avifauna, and the birds 

 are now before me. 



In Fetrochelidon htnifrons the "rump band" on the back is 

 very wide, and is joined anteriorly on either side by a very 

 distinct double line of feathers from the corresponding fork of 

 the "saddle." The ventral bands of tlie pectoral region are 

 broad but evenly feathered, while on this dorsal aspect the alar 

 tracts meet and blend with the anterior ends of the " humeral 

 tracts." This last feature is invariably the case with all our 

 Swallows, and is best marked in Clivicola and Stelgidopteryx. 



In other particulars Petroclielidon essentially agrees with 

 Progne in its pterylosis, and with the Hirundinidcs generally. 



Clielidon likewise has the posterior ends of the saddle-pteryla 

 of the dorsum joined by feather-rows, one on either side, with 

 the rump-band, which latter here is narrow again and strictly 

 defined. Neither this Swallow nor Petrochelidon have naked 

 annular areas around their eyes, nor the orifices to their ears. In 

 fact, none of these Swallows possess this last feature. Otherwise, 

 the pterylosis of Clielidon is characteristically hirundine. 



Neither Tachycineta Ucolor nor T. thalassina have the bifurca- 

 tions of the " saddle-pteryla " of the dorsum joined with the 

 " rump-band," as in the foregoing forms, but the ventral tracts 

 are here again broad and evenly feathered. 



In view, then, of the fact that the pterylosis of the Hirundinidcd 



