352 ANNALS NEW YORK ACADEMY OF SCIENCES 



is, in fact, one of the most extensive, most readily distinguished, and most 

 definable of the Tertiary series, but it still awaits accurate definition and 

 distinction, especially from overlying beds, partly owing to the fact that it 

 has been embraced imder the "Arikaree" which practically includes a con- 

 siderable part of the Miocene series. 



In the region of Agate, Sioux County, Neb., the first discoveries of 

 fossils were made by Mr. James H. Cook and his son, Mr. Harold Cook. 

 This region has been especially explored by Carnegie Institution parties 

 imder Mr. O. A. Peterson and Mr. W. H. Utterback. The Monroe Creek, 

 Lower Harrison, and Upper Harrison divisions are very distinctly separated 

 from each other geologically and faunistically. 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 Daemonelix Beds of Barbour, 

 and is characterized by the presence of Moropus, Syndyoceras, Oxydactylus, 

 Diceratherium (smaller and larger species), Parahippus, Blastomeryx, 

 Dinohyus, Thinohyus and Promcrycochosrus. Steneofiber, a castoroid, is 

 quite abundant and is frequently found in the Daemonelix spirals. The 

 origin of these spirals still remains a very difficult problem. The Upper 

 Harrison is sharply defined by the appearance of the large Merycochosrus 

 in the upper levels, by the presence of cameloids of three or four types. 

 Dinohyus persists in the lower levels but disappears above. 



A more exact determination of the geological and faimal 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. 



Mr. Chapman said, in abstract: Both the distribution and color of 

 ptarmigans are of special interest. In distribution, we have a circumpolar 

 group extending its range southward on the Arctic Alpine summit of moun- 

 tain ranges with isolated groups (for example Lagopus mutus, in the Alps 

 and Pyrenees, and Lagopus leucurus, in the Rocky JNIountains of Colorado 

 and New Mexico) occupying restricted areas at the south, which it is prob- 

 able they reached at some time during the Glacial Period. The fact that 

 the birds of these south Alpine islands are specifically like their represen- 

 tatives at the north indicates absence of differentiation since their isolation, 

 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 coloration known among birds. 



Particular attention was called to the transitional autumn plumage 

 which, in defiance of the laws of molt, is interpolated between the knowTi 



