162 UNITED STATES GEOLOGICAL SURVEY— TERTIARY FLORA. 



DRYOPHYLLUM, Debey. 



Leaves lanceolate, oblong or linear-oblong, generally dentate, rarely entire, penuinerve ; second- 

 ary nerves (in dentate leaves) subopposite, numerous, parallel, more or less curved, snbcamptodromo, 

 forking near the borders; (in entire leaves), camptodrome ; cervilles transversely decurreut, simple or 

 forking, joined by branchlets in opposite direction (Sap.)- 



This definition by Saporta is translated from Pal. V^g^t , ii, p. 613. 

 Schimper adds that this type, which originates in the Cretaceous epoch', 

 appears to have been the precursor of Quercus, Castanea, and Castancopsis; 

 that his leaves unite the characters of some Quercus and Castanea species 

 now living in the Lebanon, the Himalaya, and the mountains of Mexico. 

 He adds that it is regrettable that the species of the Upper Cretaceous of 

 Aix la Chapelle, from which this genus has been established by M. Debey, 

 have not been described to the present time, as they could throw some light 

 on the true place which they take in the vegetable world. In considering 

 the geological distribution of the species of Quercus, I have already remarked 

 that I am as yet unable to discern any sufficient character for authorizing a 

 general separation of the leaves described as Dryoiihyllum. I have, however, 

 preserved this section in deference to the authority of European writers, 

 submitting to their wider experience and more judicious discrimination. 



Dryopliylluni (Quercus) crcnatuni, Lesqx. 



Plate LXII, Figs. 10 and 11. 



Dryophyllum crenatum, Lesqx., Annnal Report, 1874, p. 301. 



Leaf subcoriaceoas, oblong-lanceolate, obliquely truncate to thb base ; borders deeply, regularly 

 undnlate or broadly crenate-dentate ; lateral veins thick, snbcamptodrome ; -nervilles thick in right angle 

 to the nerves. 



The substance of these leaves is somewhat thick, and their surface 

 coarsely marked by the nervation. As far as can be seen from the two frag- 

 ments obtained, the leaves are of medium size, linear-oblong, either equally 

 undulate on the borders or dentate, with obtuse, broad, short teeth. The 

 secondary veins are thick, flat, entering the teeth or reaching the borders by 

 their end.s, while a fork under the teeth or quite near the borders follows 

 them as a camptodrome division, anastomosing with the nervilles. The sub- 

 division of these in the middle of the areas is mostly in right angle, forming 

 ultimately small square or indistinctly polygonal meshes. The midrib is flat 

 and broad. The relation of this leaf is evidently to the Cretaceous D. lati- 

 folium, Lesqx. (Annual Report, 1874, p. 340, pi. vi, fig. 1). 



Habitat. — Point of Rocks, Wyoming {Dr. F. V. Hayden). 



