OF EASTERN PENNSYLVANIA. 47 



Sphagnum squarrosiim ; the two former in great abundance. 

 Proceeding inwardly. we find fine rootlets and grasses in- 

 tricately interwoven, and with the roots of the mosses which 

 compose the exterior. These particles occur accidentally, 

 but not designedly. The interior of the nest is lined with a 

 few herbaceous stems and leaves, mostly graminaceous in 

 character, besides a slight sprinkling of black horse-hairs. 

 From the position of the nest upon a flat surface, we natur- 

 ally expected to find the small mud-pellets upon the inferior 

 aspect, to fasten the nest upon the reposing surface. But we 

 were disappointed in this expectation. In the case of 7}/r- 

 d/is migrator ins* when the nest reposes upon a flat surface, 

 the mud on the bottom is always a noticeable feature, even 

 when the marginal rim is absent. We have recently come 

 into possession of a nest of the Robin, which is entirely de- 

 void of mud. The location of this nest, in a crotch of 

 the common juniper, closely surrounded by nearly vertical 

 branches, utterly precluded the necessity for the use of mud. 

 The nest of Sayor)iis fiisctis* about which we write, comes 

 under the same category. Reposing upon a plain solid sur- 

 face, carefully protected from the wind by an overhanging 

 bank and by local position, mud was entirely unessential. 



The absence of mud is certainly an advantage, in an eco- 

 nomical sense. To procure the amount of mud necessary for 

 a typical structure, does certainly consume a vast deal of time, 

 and entails much physical labor, without adding anything to 

 the beauty of the nest. It is true that in some situations 

 it is a highly indispensable article. The selection of a position 

 where its use can be dispensed with, bespeaks intellectual 

 improvement, and an ability to reason in details. The 

 mud-plastered nest is certainly a primitive structure. The 

 passage therefrom to the model nest is truly a decided pro- 

 gression. 



There is another advantage which the species has gained, 

 which should not l;e lightlv passed over. Mud. particular! \ 

 of the clayey kind, is very absorbent in its nature. When 



