KNOwLTox.] BIOLOGICAL CONSIDEKATIONS. 97 



species, evidently evergreen, and quite like the Q. vlrens type. Those 

 from Van Horn's ranch, on the other hand, are all or nearly all lobed 

 forms, some of them being very profoundly lobed. The}^ are evidently 

 thinner in texture than the Bridge Creek species. 



The most abundant form in the Mascall beds is Q. pseudo-lyrata of 

 Lesquereux. It is present in abundance in all collections and is hardly 

 to be distinguished from the living Q. lyrata. It was divided up by 

 Lesquereux into 5 varieties, but an examination of more than 100 

 examples convinces me that, with one exception, no satisfactory line can 

 be drawn between them, and they have been reduced to the typical 

 form. The exception above noted is that of Lesquereux's Q. j)S€udo- 

 lyrataangustiloha. After examining more than 25 more or less perfect 

 examples, it became clear that this was entitled to specific rank, and 

 it has been called Q. Merrkunl^ the varietal name cm.gustUoha being 

 preoccupied by A. Braun's Q. angustiloba. It is a very narrowly 

 lanceolate form, quite suggestive of certain leaves of Q. Tieterophylla^ 

 the so-called Bartram oak. 



A small but very perfectly preserved leaf from the same beds has 

 been called Q. duriuscula. This specimen is very close indeed to Q. 

 minor (Marsh.) Sargent, the well-known post or iron oak of the Eastern 

 United States. 



Another distinctly modern type, represented by several examples, 

 is Q. ursina^ which is undoubtedly related to Q. nana (Marsh.) Sargent, 

 the bear or scrub oak of the Eastern States. 



The only entire-leaved oak in the Mascall beds is Q. dayana, a very 

 small-leaved species of the virens type. It resembles various species, 

 such, for example, as Q. simjylex Newb., Q. convexa Lesq., and 

 Q. simidata Knowlton, but appears to differ from them all. 



The famih^ Ulmacere is represented b}^ four species of Ulmus, evenly 

 divided between Bridge Creek and Van Horn's ranch, and a single one 

 of Planera. Of the two from Bridge Creek, U. sjyedosa Newb. , is the 

 largest and finest, being from 10 to 13 cm. in length. It is very sug- 

 gestive of the living 17. americana., and was called U. pseudo-ameri- 

 cana by Lesquereux, but his name is antedated by that of Newberr3\ 

 The other species, which I have called U. Nev^herryi.^ has a much 

 smaller and narrower leaf, ranging from 6 to 10 cm. in length, and 

 less than 3 cm. in width. It was referred to XL speclosa by Newberry, 

 but seems distinct. Associated with these leaves, but especially with 

 U. specio.m., are a number of very perfect examples of the Avinged 

 fruits. They were placed with sjjeciosa by Newberry. 



The two species from the Mascall beds are TL [>lurlnerma Unger, 

 represented by a single loaf, and TJ. calif ornlca Lesq., to which sev- 

 eral small leaves are doubtfully referred. It is clear that elms were 

 not abundant in these beds. 



Bull. 204—02 7 



