354 DR. R. w. shueeldt’s morphological 
place the integument there 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. Chelidon) 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 
Ampelis, 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 Petro clielidon lunifrons 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 the 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 Stelgidop teryx. 
In other particulars Petrochelidon essentially agrees with 
Progne in its pterylosis, and with the Hirundinidce 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 Chelidon is characteristically hirundine. 
Neither Tachycineta bicolor 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 Hirundinidce 
