504 MR. G. BENTHAM—REVISION OF THE GENUS CASSIA. 
. Linneeus, in the standard second edition of his * Species Plantarum ° (1762), enumerated 
30 species, which, by the elimination of repetitions founded on imperfect materials, must 
be reduced to 25. From that time to the first decade of the present century many new 
species were added, and a still greater number of old ones redescribed under new names, 
chiefly from botanieal gardens in various parts of the world; and notwithstanding the 
general enumerations of Willdenow and Persoon, the whole genus had fallen into a state 
of the greatest confusion when Colladon took it up at the suggestion of De Candolle. 
That great master, who succeeded in forming so many botanists from among his pupils, 
always recommended to beginners the working out a special monograph as the best 
exercise, whether in systematic, physiological, or applied botany. Accordingly, M. Col- 
ladon, working under De Candolle's eye, and evidently with direct assistance from him, 
published in 1816, as his inaugural thesis for the degree of Doctor of Medicine, his * His- 
toire Médicale et Systématique des Casses, in 4to, with 20 plates. After devoting a 
eonsiderable space to the pharmaceutical products of the genus, the systematic portion 
contains an enumeration of all of the species then known, with diagnoses and descriptions, 
in as far as his materials allowed. But herbaria in those days were very scanty; and, 
owing either to the insufficiency of the characters given by various writers or to his 
having sometimes taken up species from rude drawings, out of 125 species that he enu- 
merates as more or less known, nearly one half have proved untenable. De Candolle 
himself, reworking up the genus for his * Prodromus’ nine years later, owing chiefly to the 
additions made by Humboldt and Bonpland, raised the number to 211 species enume- 
rated; but these, again, from the same causes must probably be reduced to about 110. 
After another period of twelve years the late Dr. Vogel in 1837, on the occasion of 
working up Sellow’s Brazilian Leguminosæ, found it necessary to revise the genus Cassia, 
which he did with that accuracy and ability which distinguished all his systematic labours, 
enumerating 278 species, out of which nearly 200 appear to be well established, a far 
larger proportion than is the case withany of his predecessors. During the thirty-two 
years which have now elapsed since the publication of his * Synopsis generis Cassie,” the 
only work on the subject deserving notice is Batka’s elaborate investigation of the few 
species forming the group of true Sennas. In this excellent memoir he has very 
effectually cleared up the confusion which had arisen from the vague and careless manne? 
in which the species had been noticed by the earlier and even by some more recent 
writers. In raising, however, these four species to the rank of a distinct genus, he 
appears to have been rather led away by a naturally exaggerated view of the importance 
of the characters he has elucidated in a group so long the object of his exclusive attention 
than by any general comparison with allied groups. 
In the meantime the examination of the rich stores accumulated in the Kew herba- 
rium, the study of many of the older types in the Linnzean and Banksian herbaria, the 
notes I had formerly taken at Paris and Geneva, and the collections lent to me from 
Munich and other parts of the Continent have given me the opportunity of clearing up à 
large number of the old doubtful Cassias, and of making no small an addition of now 
species chiefly from central Brazil, carrying the total number of known species, estim 
according to the views I have usually adopted, to 338, besides about a dozen published 
