872 



SCIENCE 



[N. S. Vol. XXVI. No. 677 



In the region of Agate, Sioux County, Nebr., 

 the first discoveries of fossils were made by 

 Mr. James H. Cook and his son, Mr. Harold 

 Cook. This region has been especially ex- 

 plored by Carnegie Institute parties under 

 Mr. O. A. Peterson and Mr. "W. H. Ftterbaek. 

 The Monroe Creek, Lower Harrison, and Upper 

 Harrison divisions are very distinctly sepa- 

 rated from each other geologically and faunis- 

 tieally. The remarkable deposit known as the 

 " Agate Spring Quarry " is about forty feet 

 below the summit of the Lower Harrison and 

 its fauna, and has been especially described by 

 Mr. Peterson. This is on the same level as 

 the DaBmonelix Beds of Barbour, and is char- 

 acterized by the presence of M or opus, Syn- 

 dyoceras, Oxydactylus, Dicerafherium (smaller 

 and larger species), Parahippus, Blastomeryx, 

 Dinohyus, Thinohyus and Promerycochmrus. 

 SteneofiheVj a castoroid, is quite abundant and 

 is frequently found in the Dsemonelix spirals. 

 The origin of these spirals still remains a 

 very difficult problem. The Upper Harrison 

 is sharply defined by the appearance of the 

 large Merycochcerus in the upper levels, by the 

 presence of cameloids of three or four types. 

 Dinohyus persists in the lower levels but dis- 

 appears above. 



A more exact determination of the geo- 

 logical and faunal characters of these beds will 

 mark a great advance in our knowledge of the 

 Tertiary series. 



A fine series of lantern slides illustrated the 

 paper. 



The Ptarmigan — Living and Dead: Prank M. 



Chapman. 



Both the distribution and color of ptarmi- 

 gans are of special interest. In distribution, 

 we have a circumpolar group extending its 

 range southward on the Arctic Alpine summit 

 of mountain ranges with isolated groups (for 

 example, Lagopus mutus, in the Alps and 

 Pyrenees, and Lagopxis leucurus, in the Eocky 

 Mountains of Colorado and New Mexico) oc- 

 cupying restricted areas at the south, which it 

 is probable they reached at some time during 

 the Glacial Period. The fact that the birds 

 of these south Alpine islands are specifically 

 like their representatives at the north indi- 



cates absence of differentiation since their iso- 

 lation, and consequent great stability of color 

 characters. 



The ptarmigan's seasonal changes of 

 plumage were described at length and were 

 said to furnish one of the most conclusive 

 proofs of the necessity for protective colora- 

 tion known among birds. 



Particular attention was called to the transi- 

 tional autumn plumage which, in defiance of 

 the laws of molt, is interpolated between the 

 known summer plumage and the white winter 

 plumage, to carry the bird from the end of the 

 nesting season to the season of snowfall ia 

 October. If the winter plumage were to be ac- 

 quired at the end of the nesting season, when 

 molt is apparently a physiological necessity, 

 the bird would be white before the coming of 

 snow. 



All the changes in plumage, it was asserted, 

 were accomplished by actual feather loss and 

 growth, no basis being observed for the theory 

 of change of color in the individual feather. 



The paper was illustrated with specimens 

 and a series of slides showing the White-tailed 

 Ptarmigan and its haunts on the summits of 

 the Canadian Rockies in Alberta. 



The Distribution of the Juncos, or Snow 

 Birds, on the North American Continent: 

 Dr. Jonathan Dwight, Jr. 

 The birds of the genus Junco are widely dis- 

 tributed, occupying in the breeding season the 

 whole of Canada, the higher parts of the Ap- 

 palachian, Eocky and Coast ranges of moun- 

 tains, and the pine forests of Mexico and 

 Central America. They fall quite naturally 

 into several large groups that differ widely in 

 plumage and are also farther divisible into 

 lesser groups that possess characters more or 

 less intermediate. IntergTadation between the 

 various forms seems to be complete and one 

 view is to consider them all geogTaphical races 

 of one species, but a view more in harmony 

 with the apparent facts, is to recognize several 

 of the groups as species and to consider the 

 intermediates either as hybrids or as races, or 

 perhaps as both. A blackheaded junco, for in- 

 stance, would seem to be specifically distinct 

 from a red-headed bird, because each possesses 



