CAPEIMULGID^. 307 



Family CAPRI MULGID.E, or NIGHTJARS. 



The Nightjars or Goatsuckers are a group of hirds bearing a remarkahle 

 family likenesSj but divisible into two subfamilies, the Caprimulginse and 

 the Podarginse, which are placed by Sclater in different suborders. In the 

 former, the claw of the middle toe is pectinated, the outer toe is composed 

 of only four phalanges, and the sternum has only one notch on each side of 

 the posterior margin. In the latter, the claw of the middle toe is not pecti- 

 nated, the outer toe consists of five phalanges, and the sternum has two 

 notches on each side of the posterior margin*. The Caprimulginse were 

 associated by Forbes with the Bee-eaters, Rollers, and Owls, in juxtaposi- 

 tion with the Passerine birds ; but Sclater places them with the Swifts 

 and the Humming-birds. 



Though they are associated by Huxley with the Swifts, the Wood- 

 peckers, and the Passerine birds, this writer states that in many respects 

 they present a marked contrast to these families in the modifications of 

 their cranial bones. Nitzsch says that they very nearly approach the 

 Swifts in their pterylosis ; but in their myology and digestive organs they 

 are supposed to be most nearly allied to the Bee-eaters and Rollers. 



The Nightjars moult twice in the year, in spring and autumn. 



In their external characters they are intermediate between the Swifts, 

 the Owls, and the Cuckoos, having the small bill and wide gape of the 

 Swifts, the soft pencilled plumage of the Owls, and the long tail of the 

 Cuckoos. The wing contains ten primaries, and there are only ten tail- 



* This character does not appear to be constant. Although the Caprimulginae are sup- 

 posed to agree with the Passeridee in having only one notch in the posterior margin of the 

 sternum, that of an American species, Chordeiles popetue, is figured (Baird, Brewer, and 

 Eidgway, N. Amer. Birds, ii. p. 420) with two notches, and a South-American Nightjar, 

 Steatornis caripen$ia, forms an intermediate link between the two subfamilies, having the 

 five phalanges on the outer toe and the unpectinated claw of the middle toe of the Podar- 

 ginse, but nevertheless agi-eeing with the Caprimulginse in only having one notch on each 

 side of the posterior margin of the sternum. A hasty study of both the internal and the 

 external characters of the various families of birds might almost lead to the conclusion 

 that every bird is related to nearly every other bird, that no characters are constant, and 

 that it is impossible to determine whether Any of them have any taxonomic value or 



not. 



x2 



