Apeil 9, 1897.] 



SCIENCE. 



577 



berculate mammal. The teeth of Diade- 

 madon show an incipient division of the fang 

 and closely resemble in the crowd the al- 

 leged Microledes of the Rhaetic of Germany. 

 The point of additional interest is in the 

 superior molars of an allied form, Gomphog- 

 naihus. These are, as Professor Seeley im- 

 plies, multitubercular, but they are also tri- 

 tuhereular in pattern. It is difBcult to 

 resist the inference that the four upper 

 cusps do not represent the protocone, para- 

 cone, metacone and hypocone. If this is 

 supported by further discoveries it will 

 amply demonstrate the truth of the hy- 

 jpothesis which I have long advocated, that 

 multitubercular teeth are more or less de- 

 generate derivatives of tritubercular teeth. 



Henry F. Osboen. 

 March 25th. 



ZOOLOGICAL NOTES. 



THE SHAEP-T AILED PINCHES OF MAINE. 



In the proceedings of the Portland Society 

 of Natural History (Vol. II., March 15, 

 1897) Mr. A. H. Norton remarks on the 

 distribution and relationship of the sharp- 

 tailed finches of Maine. 



He states that Ammodramus c. subvirgatus 

 breeds in the swale-bordered tide rivers, in 

 close proximity to rocky bluffs fringed with 

 black spruce, while true caudacuius of south- 

 western Maine rears its young in the broad 

 salt marshes along the sandy beaches. As 

 there are none of these low marshes in the 

 area inhabited by subvirgatus, it necessarily 

 takes the only available nesting grounds; 

 consequently the difference in the charac- 

 ter of the home of the two birds is of no ap- 

 parent significance. It is suggested that 

 ajfter the close of the glacial epoch subvirga- 

 tus followed up the receding ice until a bar- 

 rier to the bird's northward migration was 

 reached at the Gulf of St. Lawrence. 

 From this point the overflow of individuals 

 pressed westward along the Great Lakes 

 and finally covered the area now occupied 

 by nekoni. 



The author, in common with a few others, 

 is of the opinion that A. caudacutus and A. 

 nelsoni are specifically distinct, and that 

 subvirgatus is a race of the later so-called 

 species. In this we do not agree, and would 

 consider it just as logical to separate Melos- 

 piza faseiata and 3£. fallax into species with 

 montana as a race of the latter bird. 



A. K. Fisher. 



CUBBENl NOTES ON PHYSIOGRAPHY. 

 YELLOWSTONE NATIONAL PARK. 



The Yellowstone folio of the Geologic 

 Atlas, by Hague, "Weed and Iddings, forms 

 No. 30 of the series. It has six pages of 

 text, three plates with eleven admirably re- 

 produced photographs, four topographic and 

 four geologic sheets ; all at a cost of 75 

 cents. Apart from the wonders of the gey- 

 sers, the plateaus of lava beds and vol- 

 canic breccias, deeply dissected, especially 

 in the Absaroka range, along the eastern 

 border of the Park, are most notable. The 

 slender, digitate forms of some of the an- 

 cient plateau remnants are remarkably well 

 displayed on the topographic sheets. The 

 continental divides in two open valleys that 

 trench across Two-ocean plateau are pecu- 

 liar, one of them being the famous Two- 

 ocean pass, where a stream from the north 

 forms a fan at the summit of the pass, 

 turning its water rather indififerently to At- 

 lantic Creek on the east or to Pacific Creek 

 on the west. The origin of this deep and 

 rather wide valley through the plateau is 

 not stated, and our curiosity is left unsatis- 

 fied as to the reason why the Yellowstone 

 Eiver, with its relatively mature and open 

 headwater valleys, has cut a distinctly 

 young, steep-sided canyon in its more north- 

 ern course. 



BEARPAW MOUNTAINS, MONTANA. 



Messrs. Weed and Pirsson describe the 

 Bearpaw mountains of Montana (Amer. 

 Journ. Science, I., 1896, 283-301, 351-362; 



