98 University of California Publications in Geology [Vol. 7 



both of which occur at present along the Mexican border within 

 fifteen degrees of the latitude of Los Angeles. 



The collection of wading birds from the coast, while not rich 

 in point of numbers, embraces a goodly variety. Jabiru, Myc- 

 teria, Ciconia, Grus, Ardea, and Pltoenicopterus are represented; 

 yet there is no record of the spoonbill (Ajaia) or of the ibis 

 (Guara), both of which have been taken in the flesh well to 

 the northward of Rancho La Brea. 



Grouse, quail, and meleagrines have been taken in various 

 of the deposits under discussion ; yet we find there none of the 

 cracid birds such as Ortalis which occurs at present along the 

 Rio Grande valley of Texas. 



The absence of the above-mentioned species, particularly the 

 Raptores, from all the bird-bearing deposits thus far known to 

 North America becomes very striking in view of the large num- 

 ber of instances recorded of the southward retraction of species 

 and genera since the Pleistocene period. It is possible that the 

 forms mentioned above were more sensitive to the cold and were 

 driven southward before the deposition of the Pleistocene strata 

 thus far explored, or that they were, on the other hand, more 

 tropical species that have only in Recent time diffused north- 

 ward to their present range. Gyparchus is reported from the 

 Pleistocene caves of Brazil by Winge (op. eit.) which fact would 

 support the latter hypothesis. Polyborus cheriway would fall 

 in the same category with Gyparchus, being represented in the 

 asphalt by its close relative Polyborus tJiarus. The same is per- 

 haps true of the Recent species of Geococcyx found in the Son- 

 oran zone of California at the present time but represented in 

 the asphalt only by a longer-shanked form which can scarcely be 

 considered as the direct ancestor of the living Geococcyx cali- 

 fornianus. The species from the asphalt may be identical with 

 one of the species of Neomorpha from South America, comparison 

 between them having been thus far impossible. 



Approximately eighty species of true columbine birds inhabit 

 the Americas today and many of the species are forms which 

 feed on the ground and which congregate about water holes 

 to drink ; yet there is no specimen in all the material examined 

 which is referable to this group. The commonest species in the 



