54 R. W. Shufeldt 



OLIGOCENE BIRDS. 



COLYMBUS OLIGOCEANUS (sp. nOV. ?). 



{Not figured.) 



Holotype. Cat. No. 983, Peabody Museum, Yale University. Lower Willow 

 Creek, Oregon. [? Oligocene (John Day). Lull.] 



An extinct grebe based on the fossil left femur mentioned above. 

 This specimen I have compared with a large series of femora belonging 

 to existing and to fossil specimens oi JEchmophorus occidentalis, to those 

 of Colymhus holhcelli, and other grebes; but it does not represent a 

 specimen of any of these, for it is too slender and small for an Mchmo- 

 phorus or for a Holball's grebe, while it is too large for any of the 

 smaller representatives of the American Colymbidce of the genus 

 Colymbus. 



It has the form and general character of the femur in jEchmophoriis 

 or Colymhus holhcdli and the length (4.5 cms. approx.), while the 

 shaft is notably slenderer than it is ever found to be in those birds. 



The head of the bone has been broken off and lost, and the lower 

 parts of the condyles are chipped; otherwise this femur is complete. 

 Its basic color is black, which is extensively overlaid with a white de- 

 posit, giving it the appearance of many of the specimens from the 

 Fossil and Silver Lake region of Oregon. ^ I name this species provi- 

 sionally, as awaiting additional material to completely establish it. 

 As it was probably discovered in the Oligocene (John Day) of Oregon, 

 it may be known as Colymbus oligoceanus. 



Larus pristinus' sp. no^-. 



{Plate XIV, Fig. 112.) 



Holotype. Cat. No. 935, Peabody Museum, Yale University. Willow Creek, 

 Oregon. [ ? Oligocene (John Day). Lull.] 



Two fossil bones make up this lot, one being a vertebra — apparently 

 a dorsal vertebra — which may or may not have belonged to the same 

 skeleton as the second specimen did. This latter is the proximal part 

 of a left tibio-tarsus from an adult individual. It is fairly perfect as 

 far as it goes, though the cnemial processes are somewhat chipped ol¥ 

 along their anterior free margins. Notwithstanding these defects, it 

 is very clear that this fossil bone belonged to the leg of some longi- 



1 Shufeldt, R. W. " Review of the Fossil Fauna of the Desert Region of Ore- 

 gon, with a Description of Additional Material collected there. Bull. Amer. Mus. 

 Nat. Hist., Vol. XXXII, Art. VI, 123-178, PI. XV, Fig. 130. 



