1912] Miller: Pacific Coast Avian Palaeontology 99 
coast region today is the turtle-dove (Zanaidura macroura), a 
bird of wide distribution over the Austral region and even to 
the tropics. Its habits and its abundance are such that one can 
scarcely concede as possible that it could have been present 
during the deposition of the Pleistocene beds of Rancho La Brea 
and yet not be preserved as a fossil. 
Palamedea and Cariama have in their present home in South 
America a distribution and habits not unlike those of the stork, 
Eucenura. Both groups are, however, absent from the fossil 
collections. The peculiarly isolated positions which these birds 
occupy in the scheme of classification, as well as the measure of 
uncertainty as to their proper location systematically, makes any 
light that palaeontology might throw upon the subject especially 
desirable. Most careful search was made therefore to see if any 
part of the skeleton of these birds had been preserved, but 
nothing was found that resembled either species in the smallest 
degree. 
The parrot order, abundant a few degrees to the southward, 
is unrepresented in the deposits. This may be due to the fact 
that the only forest fauna which we have preserved to us (cavern 
deposits) is of Upper Sonoran and lower Transition zones, and 
thus local conditions may have been unfavorable for these birds. 
On the other hand, as suggested in the ease of Ortalis, they may 
have been driven southward before the deposition of any of 
the beds thus far explored. 
All trace of true struthious birds is lacking in the colleec- 
tions also. The northward diffusion of such forms as the eden- 
tates and Hydrochoerus among the mammals, the presence since 
early Pleistocene time of rheas in South America, the occurrence 
of tridactyl struthionids in the Pliocene of northern India, and 
of Struthiolithus in the superficial deposits of northern China, 
increase the probability that some day the discovery of true 
struthious birds in North America will be announced. The most 
potent factors that would bring about such distribution are 
first, the possible northward diffusion of rheids along with eden- 
tate mammals and, second, the passage of Struthiolithus or its 
relatives along the line of proboscidean invasion from Asia by 
way of the land bridge to Alaska. 
