140 



of this hybrid is best delayed until D. Clintoniana shall have been 

 more carefully studied. Credit for its recognition belongs to Dr. 

 Philip Dowell. 



In conclusion, I wish to thank Professor A. W. Evans, the 

 Springfield Botanical Society, Miss Margaret Slosson, and Dr. 

 Philip Dowell for favors received in connection with work on this 



paper. 



Columbia University 



AMBER IN THE LARAMIE CRETACEOUS* 



By T. D. a. Cockerell 



Recently, with the help of my wife and a number of students, 

 I have been investigating the flora of the Laramie Cretaceous at 

 Marshall, Boulder County, Colorado. This locality produces 

 much of the coal used in Boulder, and has long been known to 

 palaeobotanists, having furnished important materials to Les- 

 quereux many years ago. Periiaps the most interesting thing 

 found is a small piece of amber,t embedded in the solid rock. It 

 measures about eight millimeters by five and a half, and is trans- 

 lucent orange-brown, darker than Baltic amber. It is practically 

 insoluble in alcohol ; a small fragment left in it over night was 

 scarcely if at all diminished. In ether it eventually becomes 

 opaque and friable. In Torreya, January, 1907, Mr. E. W. 

 Berry gave a very interesting account of the occurrence of 

 amber in the Cretaceous beds of the Atlantic coast region ; it 

 now appears that this substance is widely distributed in our 

 Upper Cretaceous, and it may be possible that somewhere it will 

 be discovered in large quantities. The discovery of large pieces 

 of Cretaceous amber would be an event of the highest importance, 

 as there seems to be no reason why they should not contain 

 plant remains and insects. Cretaceous insects are exceedingly 

 desirable at the present time, to throw light on the evolution of 



* Illustrated with the aid of the Catherine McManes fund. 



fin using the term amber for the fossil resin of the Laramie strata, it is only in- 

 tended to imply that it is a transparent fossil resin, with all the appearances of the 

 substance known as amber. It is of course not the product of the same tree as the 

 Baltic (typical) amber; indeed, judging from the accompanying foliage, it is very 

 probably not even the product of a conifer. 



