366 MESOZOIC FLORAS OF UNITED STATES. 



ginous conglomerate" of C. E. Hall (p. 131), the "yellow rocks" above 

 Trenton (p. 132), and the "sand hills" east of Princeton (p. 132), all to 

 the Older Potomac. That the Older Potomac does occm' in Pennsyl- 

 vania, however, there is no doubt, and some of Mr. McGee's identifications 

 were correct. 



The discoveries of vertebrate remains in the Potomac of Maryland 

 by Mr. Hatcher greatly interested Professor Marsh, and he was anxious 

 to know what the vegetable remains indicated. He was aware that large 

 collections of plants had been made and were being worked up, and he 

 came to Washington in January, 1888, to consult with those who were 

 acquainted with the subject. It chanced that Professor Fontaine was 

 here at the time and there was a general conference on matters relating 

 to the Potomac formation. I had sent the cones collected by Mr. Hatcher 

 to Professor Fontaine and received from him an interesting letter about 

 them, dated January 5, 1888, which contains much that had not then 

 and has not since been made public. I therefore quote somewhat fully 

 from that letter: 



I am glad that you sent the cones for my inspection. I should say that they 

 are certainly cones of Sequoia. I think that the more elongate and smaller cones 

 are identical with cones of Sequoia that I found at Brooke station. You will find 

 some of these figured in the Potomac Flora. Most of those that I found were 

 imprints that were formed of cones that retained only a few scales, and the cones 

 were more or less flattened by pressure. Your cones are much more perfectly 

 shaped, although probably somewhat elongated by pressure. I did not give mine 

 specific names because they were not attached to leafy branches, and I had named 

 a number of species that had been determined by very perfectly preserved leafy 

 twigs. I thought it probable that these cones belonged to some of the species 

 named from the branches. The larger, rounded, brownish-colored cone among 

 those you sent may be of the same species with the rest, but it is exactly like cones 

 that I found at Dutch Gap attached to leafy branches of Sequoia ambigua Heer, 

 which is the most common Sequoia at that place. I remember also that among 

 the specimens collected by Mr. McGee at the head of Chesapeake Bay, those that you 

 showed me, and which contained hardly anything but angiosperms, I saw a fragment 

 of S. ambigua. My new genus Athrotaxopsis has on branches closely resembling 

 Cyparissidium, cones strikingly like those of Sequoia, but the scales have only one 

 comparatively large seed under each. Then, too, Sphenolepidium has cones in out- 

 ward form much like these. Sequoia, Athrotaxopsis, and Sphenolepidium are abun- 

 dant in the Potomac of Virginia, and I find some of these Sequoias in the Tuscaloosa 

 formation. They appear to be persistent and widely diffused forms. 



