NARRATIVE. 36 



the glove and the coat-sleeve. On the other hand, they are easily 

 killed, as they stick to their prey like bull-dogs. 



June 29^/t. — Among the birds here, the most abundant is the 

 white-throated sparrow, {Frincjilla pennsylvanica,') evidently breed- 

 ing in great numbers in the swamp, for from the top of nearly 

 every dead tree a male bird of this species was pouring forth 

 his loud, striking note, something like the opening notes of the • 

 European nightingale. The females were not to be seen, and were 

 doubtless sitting. I found the nest and new-laid eggs of the song- 

 sparrow, but could not discover those of the pennsylvanica. In the 

 evening the Professor made the following remarks on the classifica- 

 tion of birds ; 



"Animals have usually been classed merely according to the characters 

 of the adult. In some instances, however, the importance of an examina- 

 tion of the embryonic state also has already been acknowledged by natural- 

 ists. For example, the barnacle, though in fact a crustacean, has in the 

 adult state so much the appearance of a mollusk, that its true relation 

 could hardly be recognized without the investigation of the embryo, which 

 has all the aspect of the ordinary crustaceans. Hitherto embryology has 

 been applied principally to the study of functions and organs, and not of 

 classification, but I think it of the highest importance to the right under- 

 standing of the affinities of all animals. 



" Birds are at present classed according to the form of the feet and bill. 

 They form a very distinct group in the animal kingdom, all having wings, 

 naked bills, and the same general form of feet. Yet no class has puzzled 

 naturalists more. 



" Great weight has been given to the form of the toes. In one great 

 group, {Palmipedes,') at least three of the toes are united by a web (four in the 

 pelican and gannet,) throughout their whole length. In all other birds the 

 toes are free, though in some the upper joints are united. 



" The form of the claws has also been considered of great importance. In 

 birds of prey an agreement in the form of the claws is accompanied by a 

 resemblance in the shape of the bill. In others, however, this is not the case ; 

 thus the parrots, with crooked bills, and the woodpeckers with straight bills, 

 have been united as climbers. Again, the passerines, classed together from 

 the shape of the bill, agree very well in other respects ; but in the water- 

 birds, species of very various characters have been brought together. 



" Taking all these things together, ornithologists have very generally agreed 



