24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, I50 



Zone, coupled with limited material available from the Pacific side 

 in that area. Loma del Leon, or Lion Hill, the type locality of 

 pmtamensis, now submerged in the northern area of Gatun Lake, was 

 in the lower part of the Rio Chagres drainage of the Caribbean 

 slope, about 10 miles south of Colon on the northern coast. It was 

 therefore in the Caribbean area and well removed from the Continen- 

 tal Divide that separates the Chagres Valley from the Pacific. Be- 

 cause of lack of specimens from the Pacific side in the area between 

 Veraguas and the eastern part of the Province of Panama it has 

 not been recognized that these Lion Hill birds agree in color with 

 the Caribbean and eastern Panamanian population, which is accepted 

 at present as extending south through western Colombia to western 

 Ecuador, the type locality of harterti. The name panamensis of 

 1910 has application to this population, previously listed under the 

 name harterti of 1914. All birds of the Pacific side between 

 Veraguas and the central part of the Province of Panama, formerly 

 listed imder panamensis, are now placed with poliocephalus of the 

 Azuero Peninsula, as indicated above. 



Order PODICIPEDIFORMES 



Family PODICIPEDIDAE: Grebes; Somormujos 



The species of this family are among those birds most specialized 

 for life in the water. Their strongly muscled legs, placed far back 

 on the elongated, streamlined body, project at an angle that permits 

 maximum efficiency in swimming. Tail feathers are reduced to 

 hairlike plumes, which may be erected in display, or while swimming 

 in the sun, but otherwise are little apparent. The wings are small 

 but are functional except in one species, Centropelma micropterum 

 of Lake Titicaca, Bolivia. The feet, in their adaptation for swimming, 

 have the tarsi compressed, and the flattened toes, joined at the bases 

 in webs, have broad lateral lobes at the ends. One curious cir- 

 cumstance in birds of this family is found in the quantities of feathers 

 invariably present in the large stomach. The body plumage is closely 

 set and abundant, and as the birds preen, feathers are loosened 

 and are swallowed. Often the stomach is filled with these, and 

 the small pyloric lobe leading from the main stomach cavity to the 

 small intestine may have a plug of partly digested feathers. The 

 function concerned is not understood ; it is possible that the feather 

 mass aids as padding for the harder fish bones or the chitin of 

 larger insects, until these are digested. 



