THE FLORA. 



129 



able doubt that Nathorst's supposition is 

 correct, and they are consequently referred to 

 this genus. In leaves of Artocarpus incisa 

 before me the base is broadly wedge-shaped, 

 and the distance to which the lobation extends 

 decreases toward the apex, or just the reverse 

 of what occurs in A. lessigiana. The nervation 

 in the lobes is exactly the same as in the living 

 leaf, including the arching of the tertiaries, 

 the intramarginal nerve, and the secondary 

 emerging from the midrib, dividing and pass- 

 ing around on either side of the sinus. The 

 Greenland species (A. dicksoni) seems to ap- 

 proach more closely in outline to the living A. 

 incisa than the leaves under consideration. No 

 fruits or flowers have been found in the Ameri- 

 can deposits that can be referred to this genus. 



After the discovery of a well-authenticated 

 species of Artocarpus in the Cenomanian of 

 Greenland it was logical to expect to find rep- 

 resentatives in later formations on the Ameri- 

 can continent, and such has been shown to be 

 the case. The genus is now confined in its 

 native state to tropical Asia and the Malay 

 Archipelago, though once extending as far 

 north as latitude 70° in Greenland. In America 

 it has been found in the Laramie and Deliver 

 formations of the Denver Basin, in the Vermejo 

 and Raton formations of southern Colorado 

 and northern New Mexico, in the Wilcox group 

 of the Gulf region, and in the Miocene (auri- 

 ferous gravels) of California. 



The form most closely related to Artocarpus 

 lessigiana is undoubtedly^., dissecta KnoWlton, 78 

 from the Vermejo formation at Walsenburg, 

 Colo . This form is a leaf of large size, deeply cut 

 into at least three pairs of opposite lobes, the 

 lower pair remote from the ones next above and 

 connected with them by an exceedingly narrow 

 wing that is hardly more than the petiole. The 

 lower pair of lobes are also curiously cut into 

 almost to the midrib on the lower side, but the 

 upper side is attached by the whole base. 

 Otherwise the general outline, number, and 

 shape of the lobes, as well as the type of nerva- 

 tion of the lobes, are practically the same in 

 both, and, as I have pointed out in my paper on 

 the flora of the Raton Mesa region, it is entirely 

 possible that a series of leaves would show them 

 to be identical. As the facts now stand, how- 

 ever it seems best to consider them as distinct. 



» Knowlton, ¥. H., U. S. Geol. Survey Prof. Paper 101, p. 267, pi. 

 42, fig. 6, 1918. 



Occurrence: Laramie formation, Coal Creek, 

 Boulder County, Colo, (type), collected by 

 W. H. Lessig, now in United States National 

 Museum; Marshall, Colo., half a mile south of 

 railway station, in first draw north of white 

 sandstone bluff, just above the highest coal of 

 the vicinity, collected by F. H. Knowlton and 

 G. C. Martin, 1908; Cowan station, 10 miles 

 south of Denver, Colo., collected by F. H. 

 Knowlton. 



Artocarpus liriodendroides Knowlton, n. sp. 



Plate XXI, figure 3. 



Artocarpus liriodendroides Knowlton [nomen nudum], 

 U. S. Geol. Survey Bull. 696, p. 100, 1919. 



Leaf of medium size and probably mem- 

 branaceous in texture, deeply cut into at least 

 three pairs of large, opposite, distant lobes, 

 which are, with the exception of the lowest, 

 attached by the whole, evenly expanded base, 

 which continues along the petiole between the 

 lobes as a narrow web or wing and also persists 

 below the lowest pair of lobes nearly or quite to 

 the base of the petiole; lowest segment ovate, 

 rather obtuse, attached by about one-third of 

 its width; primary midrib strong, straight, 

 margined between and below the lobes by the 

 narrow wing; nervation of lowest segment con- 

 sisting of a plainly marked secondary that forms 

 a "midrib" very near the center and four or 

 five pairs of thin, alternate branches that form 

 broad loops just inside the margin; nervilles 

 anastomosing in all directions. 



This interesting specimen is, so far as known, 

 the only one found in these beds. Unfor- 

 tunately it is so fragmentary that its complete 

 size and appearance can not be determined. 

 The portion retained is about 10 centimeters 

 long, of which some 4 centimeters is taken up 

 with the petiole below the lower pair of lobes; 

 but, to judge from the undiminished thickness 

 of the midrib above, it must have been con- 

 siderably larger. The lower, nearly perfect 

 lobe, which is attached by a narrowed base only 

 5 millimeters wide, is 3.5 centimeters long and 

 1.5 centimeters broad in the middle. The seg- 

 ment next above is 2.5 centimeters broad at the 

 base and is preserved for a length of only -3 

 centimeters. None of the other lobes is as 

 well preserved, though all appear, to be opposite. 

 The nervation, marginal wing to the petiole, 

 and other features are well shown in the figure. 



