viii AtJTHOU'g PREFACE. 



for the great care and artistic skill with which she has 

 executed the lithographic plates. 



I am indebted to Mr. Gepp, of the Botanical Department, 

 for the negative from which Plate VIII. has been printed. 



A. C. SEWAKD. 



CAMBRIDGE, 



November 16th, 1895. 



