496 Berry: Origin of Stipules in Liriodendron 



In the specimen figured on Plate 41, Fig. 2, we have a much 



smaller leaf, 



iphyllum in outline • 



the blade is two-lobed at the top, with an emarginate apex, and is 

 constricted at its middle to form two large petiolar wings which 

 encircle the stem and coalesce at the point marked A y forming a 

 loose tube. These wings are very large, nearly equalling the leaf- 

 blade proper in size, and the nervation of each extends into the 

 other, as is well shown on Plate 42, Fig. 6, which represents the 

 tube slit open and spread out flat ; it will be noticed that one of the 

 primary veins takes its origin in the right-hand wing, a significant 

 fact, showing that if we are to consider these wings as stipular, then 

 we are obliged to consider the leaf-blade proper in this case as an 

 appendage of these stipules which is manifestly not the case, the 

 only alternative being to consider the wings as separated segments 

 of the leaf-blade. 



On Plate 41, Fig. 5, we have a larger leaf in a slightly more 

 advanced stage of stipular evolution ; the blade proper has a retuse 

 apex, and strongly resembles certain leaves referred to Lirioden- 

 dron priniaevum Nevvb. from the Dakota formation and to Lirio- 

 dendron simplex Nevvb. from the Amboy Clays. A wide, rounded 

 sinus separates the blade proper from the wings of the petiole, 

 which latter nearly equal the blade proper in size and are con- 

 tinuous with it by means of a narrow margin on each side of the 

 petiole. 



Plate 41, Fig. 10, shows a small oblong-cuneate leaf in about 

 the same stage of stipular development as the preceding. The 

 general shape is that of Liriophyllum obc or datum Lesq. and the 

 petiole is narrowly winged throughout its whole length ; the left- 

 hand margin expands suddenly at a point about half way to the 

 base of the petiole to form a stipule-like wing, while the right- 

 hand margin enlarges gradually until at its base it is about three 

 times as wide as it is at its narrowest part. 



Plate 42, Fig. 2, of a much larger leaf, shows us the next 

 step in the chain, with somewhat reduced wings which have be- 

 come entirely separated from the blade by an interval of petiole 

 which is one-half of.an inch long on the right sideartd five-eighth 

 of an inch long on the left side ; the finer venation of the wings is 

 somewhat transverse in its general direction, rather than longi- 



