24 



C O N T R I B U T I O N S TO PAL^ONTOLOGY 



species make up a total of 83.7 per cent of the 1700 specimens from Localities 

 P. 372, P. 374, and P. 376. At the remaining 3 localities these same species are 

 consistently among the more abundant. 



Table 1 — LeaJ counts at three localUies 



Species 



Locality 

 P. 372 



No. 



p.ct. 



Locality 

 P. 374 



No. 



p.ct. 



Locality 

 P. 376 



No. 



p.ct. 



Totals 



No. 



p.ct. 



1 . Ficus planicostata 



2. Viburnum marginatum 



3. Grewiopsis saportana 



4. Myrica torreyi 



5. Dryophyllum subfalcatum . . . . 



6. Magnoliophyllum cordatum . . 



7. Rhamnus cleburni 



8. Rhamnus salicifolius 



9. Trochodendroides nebrascensis 



10. Dombeyopsis triviaiis 



11. Cornophyllum wardii 



12. Cissites lobatus 



13. Cinnamomum affine 



14. Quercus viburnifolia 



1.5. Ficus crossii 



16. Credneria protophylloides .... 



Totals 



Total number of leaves counted . . . 



390 



241 



3 



16 



43 



81 



67 



11 



2 



20 



21 



14 



7 



12 



39.0 

 24.1 

 0.3 

 1.6 

 4.3 

 8.1 

 6.7 

 1.1 

 0.2 

 2.0 



2.1 

 1.4 

 0.7 

 1.2 



29 



4 



170 



151 



37 

 2 

 4 



24 



31 

 2 



20 



3 



2 

 2 



5.8 

 0.8 

 34.0 

 30.2 

 7.4 

 0.4 

 0.8 

 4.8 

 6.2 

 0.4 

 4.0 



0.6 

 0.4 



0.4 



16 

 19 



36 



11 



31 

 4 

 9 

 8 

 6 

 4 



10 

 3 



10 



8.0 

 9.5 



18.0 



5.5 

 15.5 

 2.0 

 4.5 

 4.0 

 3.0 

 2.0 

 6.0 

 1.5 

 5.0 



435 



264 



173 



167 



116 



83 



82 



66 



37 



31 



28 



27 



21 



19 



17 



10 



25.6 

 15.5 

 10.2 

 9.8 

 6.8 

 4.9 

 4.8 

 3.9 

 2.2 

 1.8 

 1.6 

 1.6 

 1.2 

 1.1 

 1.0 

 0.6 



928 



92.8 



481 



96.2 



167 



83.5 



1576 



92.6 



1000 



500 



200 



1700 



Where fossil fiorules can be coUected from a number of scattered localities in 

 a single formation, reUable information concerning relative abundance of species 

 can also be derived from a consideration of those species which occur at the largest 

 number of locaUties. The relative order of dominance from this point of view, 

 summarized from the local distribution of species at the 6 Medicine Bow locaUties 

 (table 4), is as foUows: 



1. Ficus planicostata 6 localities 



2. Dryophyllum subfalcatum 5 



3. Magnoliophyllum cordatum 5 



4. Rhamnus salicifolius 5 



5. Trochodendroides nebrascensis 5 



6. Quercus viburnifolia 5 



7. Cinnamomum affine 5 



8. Viburnum marginatum 4 



9. Myrica torreyi 4 



10. Rhamnus cleburni 4 



A comparison of this Ust with the 9 dominants based on leaf counts shows that 

 8 of the latter are among the 10 most widely distributed at the various Medicine 

 Bow localities. There is thus a considerable degree of correspondence between the 

 most abundant species in the individual florules and the most widespread species 

 in the flora as a whole. Only a single species, Grewiopsis saportana, among the 



