114 CONTRIBUTIONS TO PAL^ONTOLOGY 



The time relations between the Black Buttes "Laramie" and other deposits of 

 Lancian age are shown in figure 3. The transition between the so-called "Fox 

 Hills" and the overlying "Laramie" is tentativcly placed somewhat carUer than in 

 eastern Colorado because of the absence of diagnostic invertebrates of the Splmio- 

 discus zone in the " Fox Hills " of this region. It is suggestcd that in the future the 

 Black Buttes "Laramie" be referred either to the Lance formation or to the Medi- 

 cine Bow formation, to either of which it is both nearer geographically and more 

 nearlj^ synchronous in its entirety than it is to the true Laramie of the Denvcr basin. 



Vermejo-Raton floras — In south-central Colorado the terrestrial beds overlying 

 the late Montanan marine deposits have been separatcd rather arbitrarily into two 

 formations, the Vermejo and the overlying Raton. No vertebrates are known from 

 eithcr of thcse formations, so their agc determinations must bc based primarily on 

 the fossil plants and on the evidcncc from the underlying marine rocks. Thc lattcr 

 are the Trinidad sandstone, whose fauna appears to be late Montanan, probably 

 somewhat older than true Fox Hills.' The Vermejo flora, adequately described by 

 Knowlton, was referred by him to Montanan age.^ The present study agrees in 

 part with such an age assignmcnt, as is shown in the foUowing analysis of the 

 Vermejo species: 



No outside distribution 45 



Outside distribution 43 (17 in common with type Lance) 



Total number of species ... 88 



Short-ranging species : Long-ranging species : Species of uncertain range . . 2 



Montanan 8 Pre-Montanan-Montanan . . 1 



Lancian 11 Montanan-Lancian 18 



Paleocene Lancian-Paleocene 3 



Tg 22 



This is a more difficult analysis to evakiate than any of the others presented. 

 In the first place thcre are, out of 43 specics with outside distribution, 17 species 

 (40 per cent) in common with the flora of the type Lance formation. This is 15 to 

 36 per cent less than in any of the floras known to be of true Lancian age. Yet 

 there arc 1 1 out of 19 short-ranging spccies which arc rcstricted elsewhcrc to Lancian 

 age, and 3 long-ranging specics which are not known carher than Lancian time. 

 Thcse are as f oUows : 



Lancian age only: 



Aneimia supercretacea Ficus tesseilata 



Artocarpus dis.secta Magnolia nervosa 



Asplenium? coloradcnsis Palaeoastcr inquirciula 



Canna? raagnifolia (Jucrcophyllum gardncri 



Cissites panduratus \'iburnum marginatum 

 Credneria protophylloides 



Not known previous to Lancian age : 



Dillenites cleburni Qiicrcus? viburnifolia 



Sabal? ungeri 



' Lce, W. T.. and Knowlton, F. H., U. S. Geol. Surv. Prof. Papcr 101, 50. 1917. 

 Ubid., 230, 231. 



