COROCORO COPPER DISTRICT OF BOLIVIA 87 



SYSTEMATIC ACCOUNT OF THE FOSSIL PLANTS 



PTERIDOPHYTA 



Order FILICALES 

 Family POLYPODIACE^E 



Genus Polystichum ROTH 

 Polystichum bolivianum BERRY 



Berry, Proc. U. S. Natl. Mus., vol. 54, p. 117, pi. 15, fig. T, 1917. 

 PLATE VII Fig. i. 



Description. Frond character unknown. Pinnules small, 

 inequilaterally trilobate, short stalked. Length 9 mm. ; 

 maximum width, 5.5 mm. Two pinnules in 1919 collection 

 have a length of 19 mm. and a maximum width of 14 mm. 

 One small pinnule also shows an entire stout stalk 1.5 mm. 

 long. Margin entire or with an occasional mucronate tooth, 

 distinctly not spi'nulose. Texture coriaceous. The pinnule on 

 one side above the middle shows an outwardly directed, 

 conical, acuminate pointed lobe subtending an open rectangu- 

 lar sinus. On the other side one-third of the distance from 

 the base is a similar conical acuminate lobe slightly larger 

 than that of the opposite side, subtending a similar sinus. 

 About halfway to the tip of the pinnule on this side there 

 is a second vestigial lobe or mucronate tooth above which 

 the margin curves inward to the conical acuminate tip of 

 the pinnule. The venation is largely immersed in the thick 

 lamina. At the base three veins diverge at acute angles of 

 about 20 on one side and 30 on the other, the lateral ones 

 ending in the tips of the lateral lobes and the median one 

 in the tip of the pinnule. A few subordinate dichotomously 

 forking and broadly looped veinlets are faintly seen. On 

 subordinate branches from these three primary veins on 

 each side are impressions of round sori with a slightly raised 

 center, about 0.25 mm. in diameter. 



This fern is very obviously a species of Polystichum, the 

 characters of which as a whole are very well known. When 

 it comes to making comparisons with existing species of 



