Geology and Mineralogy. 489 



Colorado. This species will be found properly entered in the table 

 of distribution on page 467, and the total absence of Palms 

 in the Fort Union group was not maintained. They certainly 

 must have been rare in this section, whereas they are found in 

 nearly all the beds in Colorado and Wyoming. The same dispro 

 portion is found in the genus Cinnamomum. 



As regards the age of the Credneria beds of Europe I can only 

 say .that those of Brankenburg, where Zenker first found the 

 genus, and of Quedlinburg, whei-e a number of species occur, are 

 placed by Schimper (Traite de Paleontologie vegetale, vol. iii, 

 p. 673) in the Senonian of D'Orbigny, as are also those of West- 

 phalia, since so much more thoroughly studied by Hosius and 

 Van cler Marck, who located them in the lower portion of that 

 member. Most of the other Credneria beds lie in the Lower Qua- 

 der and should doubtless be correlated with the Cenomanian. 

 Such are those of Silesia, Saxony, Bohemia and Moravia. Schim- 

 per, however, would place Moletein, where Heer's C. macrophytta 

 was found, in the Turonian (op. cit., vol. iii, p. 59). I do not 

 certainly maintain with any force that my C. claturcefolia repre- 

 sents a true Credneria, and I have set forth in my Types of the 

 Laramie Flora (p. 98), which Professor Lesquereux had indeed 

 received but probably had not yet examined on this point, all the 

 objections raised by him to such a reference, together with some 

 others. I merely wished to make a suggestion sufficiently start- 

 ling to attract attention to this remarkable form and to call out 

 the opinions of others as to its proper affinity. 



Lester F. Wied. 



3. A pot-hole of remarkable size in Archbahl, Pa. — The pot- 

 hole recently brought to light in the coal formation at Archbald, 

 Lackawanna County, Pa., according to an account of it in the 

 Scranton Republican of November 4, 1887, has a depth of forty- 

 five feet, and a somewhat ovoidal section with the largest 

 diameter twenty feet. Its lower end was discovered in 1883 in 

 the process of coal mining, and since then it has been cleared and 

 used as an air-shaft. It is on the property of Mr. E. B. Hackley, 

 who has taken precautions, at considerable expense, to ensure its 

 preservation. It is supposed to be a product of the latter part of 

 the Glacial era, and to have been made by a great water-fall 

 descending through a crevasse in the glacier. This view implies 

 that the glacier of the region did not move on as much as ten 

 feet during the centuries in which the excavation to a depth of 

 forty-five feet was going forward ; or else that the local conditions 

 occasioning the crevasse were such as to keep the crevasse sta- 

 tionary, and without eroded sides from the water-fall, during those 

 centuries, notwithstanding the movement of the glacier. Either 

 supposition seems to be almost incredible. The other explanation 

 supposes a great river, made from the melting of the glacier, to 

 have done, the excavation by the usual river methods, that is, 

 while flowing in torrents along a shelving, rocky shore. 



4. The Lake Age in Ohio, or some Episodes in the Retreat of 

 the JST. American Glacier. — A paper on this subject by Professor 



