166 



SHORTER CONmiBrTIOXS TO GKNERAI, GEOI.onY, 1021. 



Genus LIRIODENDRON Linn«. 



Liriodendron quercifolium Newberry. 



Plate XXXVI, figure S. 



Liriodendron quercifolium Newberry, Torrey Bot. Club 



Bull., vol. 14, p. 6, pi. 02, fig! 1, 1887; U. S. Geol. 



Survey Mon. 26, p. 81, i)l. 51, figs. l-(i, 1896. 

 Bern,-, New Jersey Geol. Survey Bull. 3, p. 138, pi. 



17, fig. 1, 1911; Torrey Bot. Club Bull., vol. 39, p. 



395, 1912; vol. 44, p. 182, 1917. 

 Liriodendron pinnalijidumf Knowlton mot Lesquereux), 



U. S. Cieol. Sur\-ey Twenty-first Ann. Rept. i>t. 7, 



p. 317, 1901. 

 Liriodendron gnou-ii Knowlton (not Lesquereux'), idem. 



Leaves oblong, large, pinnatcly (iivided by 

 narrow sinuses into two to four lateral lobes. 

 Apc.x emarginate. Base truncate to somewhat 

 cordate. Length along the midrib 7 to 9 

 centimeters and probably consiilerably more 

 in some specimens, as one fragment measures 

 12 centimeters in wiilth. Width in perfect 

 specimens about 9 centimeters. Lateral lobes 

 ovate, with very acute tips, some narrowed 

 proximad, giving them an almost obovate 

 outline: intervening lateral sinuses narrow and 

 deeply cut, some reaching nearly to the midrib, 

 rounded. Some specimens have only two main 

 lobes developed on each side and are then very 

 similar to the typical modern leaf of Lirioden- 

 dron tulipifera. In these specimens, however, 

 the upper lobes are divided by a shallow sinus 

 into two acute lobules. Other specimens show 

 three lobes of equal magnitude on each side, 

 and one of the best specimens from the Wood- 

 bine sand has four nearly ec[ual lobes on each 

 side, the basal and apical pairs being somewhat 

 shorter than the medial pairs. This form of 

 leaf is very suggestive of some species of 

 Quercus, but its variations, as well as its vena- 

 tion, show that it is related to Liriodendron. 

 The petiole is preserved for a considerable 

 length and is very stout, as is the midrib. 

 There is one main secondary traversing each 

 lobe and running directh' to its apical point. 

 In addition there are one or more camptodroine 

 secouflaries in each lobe which anastomose 

 with branches from the main secondary, their 

 number being dependent upon tlie relative 

 wi<lth of the lobe; they branch from the midrib 

 at angles of about 60°. 



At first sight this species appeiirs to difTer 

 considerably from Liriodendron oblompfolium 

 and from the modern form, but this difference 

 is nut nearly as great as it .seems, and it is 

 probable that LiritHlendron qiurci/oliinn is 

 simply a variation from the common ancestor 



of the two species in the direction of Lirioden- 

 dron pinnatifdum Lestjucreux. Numerous 

 leaves of the modern tree can be found with 

 an incipient lobation suggesting Liriodendron 

 quercifolium. In these leaves, however, the 

 sinus is comparatively shallow and rounded, 

 so that the general appearance of the two is 

 not markedly similar. 



Knowlton recorded Liriodendron pinnatifi- 

 dum and Liriodendron snoirii from the Wood- 

 bine sand, but both of these prove to be frag- 

 ments of this species. 



Family TBOCHODENDRACEAE. 

 Genus TBOCHODENDROIDES Bern,', n. gen. 



This genus is proposed as a foi'm genus for 

 fossil leaves that appear to be referable to the 

 family Trochodcndraceae. It is perhaps best, 

 for the present, not to attempt a definition. 

 Attention is called in a recent publication-' to 

 the possibility that certain Mesozoic forms of 

 dicotyledons commonly referred to Celn-<itro- 

 phylhim. PopuluH, and PopulophtjUum repre- 

 sented ancestral forms of Tetracentron, Trocho- 

 dendron, and Cercidophylhim. A great many 

 Cretaceous plant species have been referred to 

 the existing genus Populus, and the e\ndence 

 for such a relationship is very slight in a num- 

 ber of forms, particuhirly among the older ones. 

 The plant from the Dakota sandstone described 

 by Lesquereux as Plii/]]il(.'i rhnmhoideiix, which 

 is present iit the Woodbine sand, is hero con- 

 sidered the type of the genus and is for the 

 present the only species definitely assigneil to 

 it. A critical survey of the late Lower (Ye>- 

 taceous and early Upper Cretaceous dicotyle- 

 dons would result in transferring a number of 

 forms to Trocliodendroides, wliich may .serve 

 for the nH'('|)tiiin of any fossil s]iecies of tiio 

 family. 



Truchudvndruidcs rhoniboidcus (Lesquereux Berry. 



I'late XXXVI, figure:.. 

 Firuxf rhomboideu.1 Lesquereux. .\mi. .lour. Sci., 2ii ser., 



vol. 40, p. 96, 1868. 

 Phyllites rhomhnidcus l.«8quereu.x, ( 'rotaceou.-' flora. \i. 1 12, 

 ].l. 6, fig. 7, 1874. 

 Knowlton, I'. S. (iool. Survey T\vciity-fir!<i .\nii. 

 llept., pt. 7, p. 317, 1!«>1. 



This species was descrila'd l)y Li'siiikmcux 

 from material foinid in (he Dakota sandstone 

 at Decatur, Nebr. He at first referred it with 

 a (|uery to FIcii.i, which it obviously does not 

 represent. Siiliseciuently lie transferred it to 



" Berry, K. W., Am. Jour. Scl., -1111 s«r., vol. 80, p. «, !»». 



