FOSSIL PLANTS OF JANCOCATA 215 



it in Bolivia south of Lake Titicaca except in the Araca 

 region but the lessened rainfall may cause it to be rarer 

 toward the southern limit of its range and its upper limit of 

 growth should also be somewhat lower than in Peru. My 

 own observations are too fragmentary to be worth much in 

 this connection. 



In extreme southern Peru and in the Titicaca Basin, that 

 is to say, in the northern part of the altiplanide, Polylepis 

 racemosa is largely, if not entirely, replaced by Polylepis 

 tomentella Weddell, a characteristic trifoliate shrubby spec- 

 ies, whose leaflets are even more similar to the fossil form. 

 A third similar species is Polylepis incana which is charac- 

 teristic of the Sierras east of Cochabamba around Duraz- 

 nillos at altitudes of between 8,000 and 9,000 feet. 



The genus Polylepis contains about fifteen existing species 

 which are confined to the Andean region of equatorial South 

 America, where they range from Venezuela and Colombia 

 southward to northern Chile and Argentina, and hitherto 

 unknown in the fossil state. 



As the fossil is a form not markedly different from a still 

 existing species in the same region it suggests that at the 

 time these sediments were deposited the altitude was not 

 very different from what it is in the present habitat of the 

 genus. This conclusion requires modification, however, 

 when the associated plants are taken into consideration and 

 will be discussed in the section of the present contribution 

 devoted to the analysis of the fossil flora. 



The only fossil plant from other regions that resembles 

 the present species is Raphiolepis indica Lindley an existing 

 Rosaceous form of southern Asia which Marty 6 has identi- 

 fied from the Mio-Pliocene of Central France. 



6 Marty, P., Revue General Botanique, tome 32, p. 24, pi. 12, 

 fig. 5, 1920. 



