217 



This is the only monstrosity of its kind on tliis species which 

 has come to my notice. It is of interest to note the resemblance 

 of fruit and joint in such cylindrical opuntias as the cholla {0. 

 fub^ida), in which there occurs normally and year after year a 

 buddinj^-out from fruits in manner apparently quite like the 

 branching of the joints of the plant. As a consequence of this 

 proHfcration and where undisturbed the fruits of cholla are very 

 numerous, forming large clusters. In other opuntias also the 

 fruits bear both spines and prickles and in this habit they recall 

 the purely vegetative part of the plant. Whether, however, the 

 peculiar fruit of the prickly pear above described is to be con- 

 sidered as indicating a caulomic tendency as exhibited b}' cholla 

 and in other ways by other opuntias might be questioned.* 



W. A. Cannon. 



Deskrt Botan'icai, Laboratory, 

 Tucson, Arizona. 



REVIEWS 



Christensen's Index Filicumf 



The lack of a satisfactory index to the species of ferns has 

 been one of the greatest drawbacks to the systematic study of 

 this group of plants. Moore's attempt % in the early si.xties 

 proved unsatisfactory and incomplete, since the printing ceased 

 before the genera commencing with the letter G were completed. 

 The parts that were published are not sufficiently exact for pres- 

 ent day citation, since dates of publication were rarely given. 

 Salomon's Nomenclator§ was carried through the alphabet but 

 was incomplete at best and gave no citations whatever, thus 

 proving a scarcely useful list of mere names. The need of a 

 thorough index has been so much the more keen (i; since 



* Compare also the sketch of Optintia Ficits-iiidiia in Engler & Prantl's Die 

 Natiirliclieii Pflanzenfamiiien, 3'''': 170, in which the fruit is shown sending out roots 

 and new shoots quite like the joints of the plant. 



tChristensen, C. Index Filicum, sive enumeratio omnium generuni specierunKjue 

 Filicum et Hydropteridum ab anno 1753 ad annum 1905 descriptorum adjectis synon- 

 ymis principalibus, area geographies, etc. Hafniae 1905 apud 11. Hagerup. [Price 

 3s. 6d. per fascicle.] 



J Moore, T. Index Filicum. London, 1857-1863. 



^ Salomon, C. Nomenclator der Gefasskryptogamen. Leipzig, 1883. 



