152 DIVER 



attracted the attention of Willugliby more than two hundred years 

 since. On the other hand, Brandt, and Rudolph Wagner shortly 

 after (Naumann's Vogel Deutschlaiids, ix. p. 683, xii. p. 395), had 

 already shewn that the structure of the knee-joint in the Grebes 

 and Divers differs in that the former have a distinct and singularly- 

 formed jyatella (which is undeveloped in the latter) in addition to 

 the prolonged, pyramidally-formed, procnemial process — which last 

 may, from its exaggeration, be regarded as a character almost 

 peculiar to these two groups.^ The evidence furnished by oology 

 and the newly-hatched young would seem to favour Brandt's views ; 

 and, without according too much weight to such evidence, it cer- 

 tainly ought to be considered before a decision is reached. The 

 abortion of the recfrices in the Grebes, while these feathers are 

 fairly developed in the Divers, is another point that helps to 

 separate the two Families ; but until their morphology has been 

 worked out nothing can be safely averred on the subject. 



The commonest species of Colymbus is C. sepfentrionalis, known 

 as the Red-throated Diver from an elongated patch of dark bay 

 colour which distinguishes the throat of" the adult in summer-dress. 

 Notwithstanding this ornament, it is the least conspicuous, as it is 

 also the smallest, species of the genus, the back and upper plumage 

 being of a blackish-brown with a few insignificant white spots, 

 while the head and sides of the neck are ash-coloured, bounded by 

 a long nuchal band, which lower down advances towards the 

 breast, of feathers marked with black, grey, and white, to form 

 regular stripes. Immature birds want the bay patch, and have 

 the back so much more spotted that they are commonly known as 

 "Speckled Divers." Next in size is the Black-throated Diver, 

 C. ardicus, having a light grey head and a gular patch of purplish- 

 black, above which is a semi-collar of white striped vertically with 

 black, while two patches on the black back, between the shoulders, 

 as well as the scapulars, are conspicuously marked with large sub- 

 quadrangular white spots. Still bigger is the Great Northern 

 Diver, C. glacialis or torquatus, with a glossy black head and neck, 

 two semi-collars of Avhite and black vertical stripes, and nearly the 

 whole of the black back and upper surface of the wings beautifully 

 marked with white spots, varying in size and arranged in belts. ^ 

 Closely resembling this bird, so as to be most easily distinguished 

 from it by its ivory-white or yellow bill, is C. adainsi, the specific 



^ GaiTod, in his tentative and chiefly myological arrangement of Birds 

 {Proc. Zool. Soc. 1874, p. 117), placed the Colymhidaz and Podicipedidje in 

 one Order (Anseriformes) and the Alcidse in another [Charadriifonnes) ; but the 

 artificial nature of this assignment may be realized by the fact of his considering 

 the other Families of the former Order to be Anatidas and Spheniscidas. 



^ The osteology and myology of this species are described by Dr. Coues 

 {Mem. Boston Soc. Kat. History, i. pp. 131-172, pi. 5). 



