ON THE NATURAL HISTORY OP THE NIGHTINGALE. 221 



Blackcap, and other Fauvets, for which it has very little or no af- 

 finity. I do not, at present, think it necessary to enter deeply into 

 the subject, but may here just cursorily remark that the immature, 

 or nestling, plumage of birds, furnishes always a very good negative 

 test of affinity ; species which differ strikingly from each other in 

 this garb, being never very closely allied. In the Deniirostral (or 

 notch-billed) division of perching birds ( InsessoresJ, there is an 

 extensive host of species, forming divisions of three ndiinvdXJamilies, 

 all of which are allied to each other, and possess a variety of cha- 

 racteristics in common, one of which is to have their first plumage 

 invariably mottled, in the manner already detailed of the young 

 Nightingale ; which style of marking, it is to be observed, is pecu- 

 liar among the De?itirostres to these birds, and, indeed, the only 

 instance I know of its occurring in any other group, is in the soli- 

 tary case of the Tree-creeper (Cerlhia familiaris). The three 

 siib-families to which I have alluded are the Merulinoe, or typical 

 major group of the Thrush family (Merulidce) ; the Saxicolinaz, or 

 Robin and Chat division of the Petty chaps or Warbler family ( Sylvu 

 adcej ; and that division (as yet unnamed) of the Muscicapidce, or 

 Flycatcher family, to which the European species belong. The 

 Nightingale will therefore, in all probability, appertain to one of 

 these (all the remaining Dentirostres having their first plumage of 

 quite a different character) ; and to classify it naturally, and accord- 

 ing to its true affinities, we have, of course, only to place it beside 

 those birds which most resemble it in all their general characters. 

 Is very closely allied to certain of the smaller Thrushes of Ame~ 

 rica. — We find, by far, the nearest approximation, then, in an 

 American group of Thrushes (Merula), of which the Tawny and 

 Hermit Thrushes, of Wilson's work, are among the most Nightin- 

 gale-like of all. Indeed, the whole of the spotted-breasted Thrushes 

 of America (I exclude, of course, the genus Orpheus) are very 

 nearly allied to Philomela ; they have the same predominant ru- 

 fous tint, and many of them the same form, including the long slen- 

 der tarsus ; and the habits of even Merula mustelina, the species 

 which approaches nearest of all to our Song Thrush, as described by 

 Wilson (who entertained no idea of the resemblance), hardly differ 

 in a single point from those of the European Nightingales. They 

 are solitary birds at all seasons, and (like the Nightingale) they even 

 migrate solitarily, which is contrary to the habit of the more typical 

 Thrushes ; and they are also considerably more retiring and hidling 

 in their general manners than are those standard species of Merula 

 with which only we are familiar. So closely, indeed, do some of 



