THE FLORA. 



153 



half the length of the blade and end in the 

 margin, as do all the branches; upper pairs of 

 secondaries dividing the blade into two or 

 three approximately equal divisions, arising at 

 a slightly more acute angle than the lower pair 

 and terminating in the margin, the lower pair 

 with one or two branches on the lower side; 

 nervilles rather faint, percurrent, and at right 

 angles to the midrib. 



This species is represented by eight or ten 

 more or less perfect examples, four of which 

 have been figured. They range, so far as can 

 be made out, from 4.5 to about 5.5 centimeters 

 in length and from 3 to 4 centimeters in 

 width. They are elliptical or broadly oval, 

 with a rounded base and an apex which is 

 similarly rounded to an abruptly acuminate 

 point. Each specimen has three or four 

 pairs of secondaries, the lowest of nearly the 

 same size as the midrib and emerging at the 

 top of the petiole and bearing three or four 

 branches on the lower side, while the other 

 secondaries are remote and simple or once or 

 twice branched. The margin is finely serrate 

 from a point one-third or more above the 

 base. 



There is considerable uncertainty as to the 

 proper generic reference for these little leaves. 

 They have, for example, the same size, shape, 

 and superficial appearance as Ficus plani- 

 costata Lesquereux, 40 but they differ at once 

 in the serrate margin and craspedodrome 

 instead of camptodrome nervation: The 

 broader forms have also some resemblance 

 to Cissus lobato-erenata Lesquereux, 41 but 

 that species differs in having an irregularly 

 toothed margin and a different, looser nerva- 

 tion. Morus italica Massalongo, 42 from the 

 Italian Tertiary, is very suggestive of this 

 species but differs in being five instead of 

 three ribbed from the base and in minor 

 details of nervation. At one time it was 

 thought that these specimens should be re- 

 ferred to Viburnum, as certain .of the more 

 rounded forms have the shape and much the 

 nervation of V. dichotomum Lesquereux, 43 but 

 that species differs in having more prominent 

 teeth and a markedly flexuose midrib. Sev- 



« Lesquereux, Leo, The Tertiary flora: U. S. Geol. Survey Terr. 

 Rept.. vol. 7, pi. 31, figs. 3, 4, 5, etc., 1878. 



« Idem, pi. 41, fig. 3. 



« Synop3is florae fossilis senogalliensis, pis. 10-11, fig. 10, 1859. 



« Lesquereux, Leo, The Tertiary flora: V. S. Geol. Survey Terr. 

 Rept., vol. 7, pi. 88, fig. 6, 1878. 



eral of the broader forms approach V. lakesii 

 Lesquereux 44 in the configuration of the base, 

 but that species differs in being three-lobed 

 and in having a different branching of the 

 lower secondaries. Among living species of 

 Viburnum this much resembles V. dilatatum 

 Thunberg, from Japan, which has the shape 

 and dentition but differs in having eight or 

 more pairs of secondaries. From V. dentatum 

 Linne it is also distinguished by much the 

 same characters. 



But, all things considered, it seems best to 

 refer this form to Ceanoihus, as it is, for in- 

 stance, very similar to certain of the rounder- 

 leaved forms of the living 0. americanus LinnS, 

 and more especially to a form presumed to be 

 a hybrid of this, known as 0. azureus, culti- 

 vated in the parks at Washington, D. C. All 

 the fossil leaves, however, /appear to be more 

 nearly elliptical than either of the above- 

 mentioned forms. The marginal teeth are 

 similar to those in the living species except that 

 they do not occur on the lower third of the 

 blade. This species differs from C. azureus in 

 its larger size, more rounded form, serrate 

 margin, and craspedodrome nervation. 



Occurrence: Laramie formation, Erie, Colo., 

 collected by N. L. Britton about 1885. 



Ceanothus ovatifolius Knowlton, n. sp. 



Plate XXV, figure 3. 



Ceanoihus ovatifolius Knowlton [nomen nudum], U. S. 

 Geol. Survey Bull. 696, p. 151, 1919. ' ^ 



Leaf cuneate-ovate, 3 centimeters long, 1.5 

 centimeters wide, long wedge-shaped at the 

 base, rather abruptly acuminate at the apex; 

 margin entire; nervation camptodrome, of 

 about five pairs of opposite or subopposite ' 

 secondaries, the lower pair arising from the 

 very base just at the margin of . the blade, 

 thence running up for nearly two-thirds the 

 length of the leaf and there joining the third 

 pair of secondaries, which in turn arch to the 

 pair next above, the whole forming a line just 

 inside the border; finer nervation not pre- 

 served. 



This leaf, which is the only one found in the 

 collection, is referred with considerable cer- 

 tainty to the genus Ceanoihus, being in shape 

 quite like the living C. ovatus Desfontaines or . 

 C. velutinus Hooker and in nervation strik- 



« Hem, pi. 87, fig. 13, 1878. 



