NO. 2151. FOSSIL PLANTS FROM FLORISSANT— KNOWLTON. 269 



This species is named in honor of Mr. T. E. Williard, of the United 

 States Geological Survey, who has done much efficient work in select- 

 ing and preparing the Florissant collections for study. 



Family HYDRANGEACEAE. 



HYDRANGEA? SUBINCERTA Cockerell. 



Hydrangea f subincerta Cockerell, Bull. Amer. Mu9. Nat. Hist., vol. 24, 1908, 

 p. 92, pi. 9, fig. 32. 



A single example in the Hambach collection that is evidently this 

 species. The original specimen is said by Cockerell to be without 

 nervation, but the present one has faint indications of very thin longi- 

 tudinal ribs, there being about four in a sepal. The other nervation 

 is obsolete. 



HYDRANGEA? FLORISSANTIA Cockerell. 



Hydrangea florissantia Cockerell, Amer. Joum. Sci., vol. 26, 1908, p. 67, fig. 



(in text) 2; p. 541. 

 Rhus rotundifolia Kirchner, Trans. St. Louis Acad. Sci., vol 8, 1898, p. 184, 



pi. 12, fig. 2. [Not Hydrangea rotundifolia Rafinesque.] 



Type of Rhus rotundifolia. — Cat. No. 33,676, United States National 

 Museum. 



The type-specimen of Kirchner's Rhus rotundifolia is so exactly 

 similar to the figure of Cockerell's Hydrangea florissantia that the 

 two figures might almost have been made from the one specimen, 

 and there is of course absolutely no question as to their identity. 

 That they are properly referred to Hydrangea, however, is by no 

 means so certain. Each of the individual segments, whatever their 

 nature may ultimately be proved to be, is distinctly provided with a 

 short thick petiole 1 or 2 mm. in length, whereas in Hydrangea the 

 sepals are sessile or even slightly united at base. In Hydrangea hen- 

 direi (Ward) Knowlton,* from the Mascall formation of Oregon, the 

 the sepals are completely sessile if not indeed slightly united at base. 

 It seems a suspicious circimastance that the only specimens found 

 (or figured) should both lack the fourth "sepal" which was presum- 

 ably present if it really is a sterile flower of Hydrangea. It is just pos- 

 sible that this may be a compound leaf of three leaflets, and not a 

 flower at all. 



Bull. U. 8. Geol. Surv., No. 204, 1902, p. 60, pi. 9, figs. 6. 7. 



