NO. 2229. FOSSIL PLANTS FROM BOLIVIA— BERRY. 107 



BOTANICAL CHARACTER. 



The present contribution enumerates 85 different species of plants 

 from Bolivia, of which 82 come from the tuffs of the historic Cerro de 

 Potosi. Collections from these tuffs studied by Engelhardt in 1887 

 and 1894 resulted in making known 44 species of fossil plants, and 

 Britton in 1893 added 11 species. The flora as at present known is 

 remarkable for the great predominance of small individuals in it and 

 for the large numbers and variety of its Leguminosae. It contains 

 the representatives of 6 Pteridophytes (all ferns), 1 coniferophyte (a 

 Podocarpus) and 75 angiosperms, of which 3 are Monocotyledons and 

 the balance Dicotyledons. Of the latter there are 8 of doubtful affin- 

 ities, 5 Gamopetalae, and 59 Choripetalae. The Dicotyledonae rep- 

 resent 41 genera in 20 families and 13 orders. The largest genus is 

 Cassia with 10 species. The most abundant individual forms are 

 Myrica hanksioides and Calliandra obliqua. Much the largest order 

 is the Rosales, represented by the families Saxifragaceae, Cunoni- 

 aceae, Mimosaceae, Caesalpiniaceae, and Papilionaceae, containing 

 altogether 47 species, the great majority belonging to the last three 

 families. There are 13 species of Mimosaceae representing the 

 genera Acacia, Inga, Pithecolohiwm, Mimosa, Mimosites, Calliandra, 

 and Enterolobium. There are 17 species of Caesalpiniaceae repre- 

 senting the genera Cassia, Caesalpinia, Caesalpinites, Copaifera, 

 Bauliinia, and Peltophorum. There are 12 species of Papihonaceae, 

 representing the genera Amicia, MacTiaeriwn, Dalbergia, Desmodium, 

 Drepanocarpus, Aeschynomene, Sweetia, LoncTiocarpus, and Platy- 

 podium. There are thus 9 genera of Papilionaceae, 6 of Caesal- 

 piniaceae, and 7 of Mimosaceae. No other families are represented 

 by more than two genera and most of them have but a single genus 

 present. Similarly all of the nonleguminous genera except Myrica 

 and Weinmannia are represented by a single species. 



There are three or four species of Myrica in the fossil flora of 

 Potosi, the only common and clearly defined of which is Myrica 

 banksioides Engelhardt, and I am not sure but that Myrica wendtii 

 Britton and Myrica engelhardtii Britton are not simply large and 

 small variants of this species. Myrica potosina Britton is not a 

 Myrica, and while Myricophyllum, species Engelhardt, is clearly dis- 

 tinct from all of the preceding and apparently represents a perfectly 

 good Comptonia-hke Myrica, it is represented by such incomplete 

 material that Uttle can be said about it. 



Myrica is a very old generic type with a large number of fossil 

 species, ranging in age from the Mid-Cretaceous to the present. The 

 still existing species are relatively few in number, are widely scattered 

 geographically, and represent survivors from a Tertiary cosmopolitan 

 distribution. 



