COLYMBIDJS. 485 



Order XVIII. PYGOPODES. 



(By W. E. OGILVIE-GIiAXT.) 



Skull holorhinal and scliizogiiathous : iiares pervious ; vomer 

 cleft posteriorly for about h or ^ its length ; basipterygoid processes 

 absent ; lachrymal not extending downwards to join the quadrato- 

 jugal bar ; quadrate with an elongate orbital process ; maxillo- 

 palatine processes laminate, not rod-shaped ; dentary suture of 

 mandible more or less completely obliterated ; anguLire truncate 

 posteriorly ; fnrculum without a facet for articulation with the 

 acro-coracoid ; pre-ilia not rising up to meet in the middle line 

 above the fused neural spines of the synsacrum ; post-ilia much 

 longer than the pre-ilia and vertically compressed ; tibio-tarsus with 

 the cnemial crest produced upward far beyond the articular surface of 

 the femur ; tarso-metatarsus laterally compressed ; outer toe longest, 

 llhamphotheca simple. Nestling nidifugous. (W. P. Pycraft.) 



Key to the Families. 



I. Hallux on a level with the other toes ; 



front toes united one to the other 

 by a web ; tail composed of 18 or 

 20 short stiff feathers 1 . Colymbidae, p. 485. 



II. Hallux raised above the level of the 



other toes ; toes provided with wide 

 lateral lobes united at the base ; tail 

 vestigial 2. Podicipedidae, p. 502. 



Family 1. COLYMBID.E. 



Supraorbital grooves very deep ; temporal fossas deep, separated 

 one from another by a median sagittal ridge ; lachrymal more or 

 less fused with the nasal ; all the vertebrae free ; spina externa, no 

 spina interna; mctastcrnum projecting far beyond the posterior 

 lateral processes; ventral lip of the coracoid groove moderately 

 developed ; post-ilia not meeting above the neural spines of the 

 synsacrum ; tibial bridge ossified ; patella vestigial ( W. P. Pycraft). 

 Sterno-tracheal muscles symmetrical {H. Gadow). Accessory semi- 

 tendinosus absent {A. H. Garrod). Two carotids (^1. H. Gar rod). 

 1 1 metacarpo-digital remiges. Hallux on a level with the other 

 toes, which are united one to the other by a web. Tail composed 

 of 18 or 20 short stiff feathers. 



