''^I)"''] PROCEEDINGS OF THE NATIONAL MUSEUM. 25 



considered as identical with this, are found in the lower Atanekerdkik in 

 Greenland. All the other varieties are either from this locality or 

 from Asuk and Isunguak in Grreenland, bat nevertheless Heer did not 

 find any reason for separating them, on the contrary, he found " insensi- 

 ble gradations" between them, and it seems that it is especially in re- 

 gard to the understanding of the intergrading forms that Dr. Newberry 

 does not agree with Heer. 



What then, is the difference between Dr. Newberry's two leaves of 

 his species L. prinucDum and L. Meekii, both from Nebraska, when 

 compared with those called L. MeeJcii var. prinuvva and (jemima of 

 Heer obtained from Greenland? I do not think there is any ditter- 

 ence in the size as far as concerns the variety genuina, and in the 

 other one, the variety primcvva, the leaf from Greenland is somewhat 

 defective, but shows, nevertheless, the emargiuate summit and a little 

 more than the half part of the blade, and this leaf does not differ more 

 from Dr. Newberry's drawing than most of the variations I have fig- 

 ured from the living tree. Both of them show a somewhat rounded 

 base, as if there was a tendency toward forming a basal lobe, and at 

 the superior margin there is a distinct and roundish lobe. The nerva- 

 tion is entirely the same. The two forms primrcva and genuina are 

 by Heer united with the species MeeJcii, and it seems to be done so with 

 the best reason; I would merely object to consider them as two differ- 

 ent varieties, since the only difference is to be found in the number of 

 lobes, there being two pairs in genuina and only one, or rather one pair 

 of distinct lobes and another pair very obtuse, forming an expansion at 

 the base of the blade of primwva. Do we not find a similar variation 

 among some of the leaves from the living tree? I will merely call 

 attention to a leaf, Plate vi, Figs. 19 and compare it with another 

 one, Plate v, Fig. 11. It seems to me that we have here a very good 

 analogy in regard to this question. If we examine the leaf on Plate v. 

 Fig. 17, which is from the same young tree as the first one, Fig. 10, we 

 must certainly wonder that Dr. Newberry was unable to find any inter- 

 grading forms. 



If we now consider the other varieties of L. Meekii, figured by Heer 

 (/. c), in his Plates xxii, xxiii, and xlv, we shall then again find a 

 great mutual agreement. Tliese leaves are almost entire or approxi- 

 mately obcordate, especially the variety obcordata, Plate xxiii. Fig. 4 

 (/. c). The difterence between these forms is very slight and limited, 

 almost wholly, to the relative proportions of size. The variety obcor- 

 data shows this characteristic shape, while the leaves of Marcouana 

 are longer and narrower, with the base of the blade tapering into the 

 petiole. The third one, muoronulata, seems to be closely allied to the 

 variety Marcouana, but shows a small point at the end of the midrib, a 

 character, which has also been shown, however, in the leaf. Fig. 5, Plate 

 XXII (/. c.), of Marcouana. This point seems to be analogous to the 



