^'%^o"'] PROCEEDINGS OF THE NATIONAL MUSEUM. 27 



seciindariis piuuatis subsiiuplicibas." Four varieties of this species 

 have beeu eimiiierated by Massaloiigo : 



A. L. Procaccinii v. helvetica. 



B. L. Procaccinii v. acutiloba. 



C. L. Procaccinii v. ohtusiloha, (a) suhattenuala, (/5) rotundala. 



D. L. Procaccinii v. incisa. 



The variety helvetica was first cousidered as a good species {L. lielvet- 

 icum) by Heer,* but after seeing the figures of L. Procaccinii, he agreed 

 perfectly with Massalougo in referring it as a variety of this. 



If we now turn to the drawings of this variety,! given by Heer, we 

 shall see a very striking agreement with our recent species ; indeed, it 

 is rather difficult to find any essential differences. But the leaf, figured 

 by Heer (Fig. G) shows, moreover, that the blade tapers into the petiole 

 in a somewhat larger degree than we find in the recent species, and 

 this seems to be characteristic of some of the other varieties of L. Pro- 

 caccinii. There is, however, in Heer's Uhrwelt der Schweiz (1S79) a 

 drawing of a leaf (Fig. 223), which has been identified as L. Procaccinii, 

 where there is a distinct sinus at the inferior margin of the leaf instead 

 of, as mentioned above, the blade tapered into the petiole. Heer's re- 

 mark| abont this leaf from Iceland, collected by Japetus Steenstrup, 

 is very interesting. He calls attention to the presence of five lobes, 

 but does not think it correct, however, to separate it from the leaves of 

 L. Procaccinii, collected by Senegaglia and Eriz, even if these do not 

 show more than three lobes. He mentions the fact that the leaves of 

 our recent Tulip-treo very often show five lobes or sometimes no lobes 

 at all, therefore he does not consider the number of lobes as a charac- 

 ter of much importance. Now, in regard to the systematic position of 

 this leaf from Iceland, Heer has remarked not only that there is a great 

 accordance between this and the other leaves of the same species from 

 the continent, but even that these are clearly allied to the living spe- 

 cies. There is another leaf considered as identic with L. Procaccinii, 

 and figured by Heer in his Flora fossilis arctica,§ of which the margin 

 seems to have been entire, without lobatiou, and if the identification 

 be correct, since the fossil is verj^ poor, L. Procaccinii has then shown 

 the same variation as the recent, with the lobes wanting, and I should 

 then compare this form with the leaves figured on Plate viii. Figs. 

 33, 36, and 37. 



In regard to the other varieties of L. Procaccinii, described in Flora 

 del Senigalliese, we see here on Plate vii, Fig. 23, a leaf of acutiloba, 

 the lobes of which are certainly very acute, but does not seem to differ 

 from the variety Helvetica in any other respect, and might possibly cor- 

 respond to Michaux's acutiloba of the recent species, at least, as a sim- 



* Oswald Heer: Flora Tertiaria HelvetiiB, iii, 1859, p. 195. 



\Ibid., Vol. I, Plate cviii, Figs. 6 and 6b, and Flora Fossilis Arctica i, 1868, Plate 

 XXVII, Fig. 5. 



t Ibid., Flora Tert. Helv. iii, 1859, p. 319. 

 § Ibid., Vol. I, 18(i8, Plato xxvi, Fig. 7b. 



