Febeuaey 14, 1896.] 



SGIENOE. 



243 



"it seems certain that the formation (James- 

 burg) was produced during the submergence of 

 the area which it covers;" secondly (p. 128), 

 that "the period of submergence must have 

 been short;" and thirdly (p. 129), that "the 

 amount of erosion accomplished since the de- 

 position of the Jamesburg is slight. This is 

 shown ^ ^. j(. by the undissected flats of this 

 material, even where in close association with 

 considerable streams, j^ ^ ^ Either the forma- 

 tion is very recent, or conditions since its de- 

 velopment have been most unfavorable for 

 erosion j^ ^ ^ . The small amount of erosion 

 which it has suffered seems hardly consistent 

 with its correlation with the earliest glacial 

 epoch." 



In order to understand the distinct advance 

 here made, one has but to refer to Prof. Cham- 

 berlin's article in the American Journal of 

 Science, for March, 1893, pp. 191, 192, where 

 he enumerates among the features which he 

 thinks 'may be accepted as demonstrative,' 

 first, that ' ' an older fluviatile deposit (the Phil- 

 adelphia Brick Clay) is to be associated in age 

 with the old glacial drift, ' ' and ' ' that after the 

 formation of this older river deposit, which took 

 place at a low altitude and a low gradient, there 

 was an epoch of elevation and erosion, during 

 which the Delaware cut its channel down to the 

 depth of 200 or 300 feet below the upper old ter- 

 race." It would seem now that this interpreta- 

 tion must be abandoned for the Delaware, as a 

 similar interpretation had to be abandoned for 

 the gravel terraces near the junction of the Cone- 

 wango and the Allegheny Rivers two years ago. 

 Mr. Salisbury is undoubtedly correct in believ- 

 ing that these high level gravel and clay de- 

 posits in the Delaware Valley, in the vicinity 

 of Trenton, are of comparatively recent deposi- 

 tion. They are not older, but younger, than 

 the erosion of the rock channel of the Dela- 

 ware. 



I may say in conclusion, also, that the investi- 

 gations of Prof. E. H. Williams, in the Lehigh 

 Valley, which have been too little noticed, 

 seem positively to show that the river channels 

 of that whole region had been worn to nearly 

 their present depth of rock bottom before the 

 earliest period of glaciation. I trust that re- 

 newed attention will be attracted to this diffi- 



cult problem concerning which so many facts 

 have now been accumulated. 



G. Fkedbeick Weight. 

 Obeelin, O., January 29, 1896. 



ANCIENT MEXICAN FEATHER WOEK AT THE. 



COLUMBIAN HISTORICAL EXPOSITION AT 



MADEID, 1892. 



To THE Editor op Science : Under the- 

 above title a contribution of mine has appeared 

 in the recently issued Report of the U. S. Com- 

 mission on the Madrid Exposition, Government 

 Printing Office, Washington, 1895. Owing to 

 the fact that the proofs were not sent to me for 

 revision, my paper contains several typograph- 

 ical errors, three of which particularly demand 

 correction. It being too late to rectify these 

 errors by any other means, I have adopted the 

 present method of doing so, with the hope and 

 earnest request that possessors of copies of the 

 report will duly note them therein, in order ta 

 prevent future misunderstandings. On page 

 382 read that I identified the shield ' of Phillip 

 II.' at the Royal Armory, Madrid, as being of 

 Hispano-Mexican workmanship, in ' October, 

 1892,' instead of ' 1893,' as printed. 



On page 335 read the 'tiny,' instead of the 

 wing feathers * * * that grow on the heads and 

 breasts of tropical humming birds. 



On page 337 read Mr. Phillip Becker instead 

 of ' Bectier(?) ' I need scarcely state that, in 

 my original text, the name of my late, highly 

 esteemed friend, is correctly given and is not 

 followed by an interrogation point. 



Thanking you, in advance, for kindly affiard- 

 ing me the opportunity to do myself justice. 

 Yours truly, 



Zelia Nuttall. 



January 14, 1896. 



SCIENTIFIC LITERATURE. 



NEW DATA ON SPIEULA. 



Zoology of the Voyage of H. M. S. Challenger : Part 



I., XXXIII. Report on Spirula. By T. H. 



Huxley and P. Pelseneer. viii., 32 and 



12 pp. 4°, and six plates. 1895. 



The eighty -third and last part of the zoologi- 

 cal series of reports on the scientific results of 

 the Challenger expedition could not be issued 

 in one of the zoological volumes on account of 

 delays in its preparation. These delays were 



