MASSEE: A MONOGRAPH OF THE MYXOGASTRES. 173 
avold a definite conclusion as to the animal or plan nature of the 
Myxogastres, and while awaiting the acquisition of further facts, to 
keep an open mind on the subject. 
In the second part of the volume, the setae are dealt with 
from the systematist’s point of view and in a manner to which, with 
our present knowledge, it is scarcely possible to take the slightest 
objection. As a matter of fact, this is by far the most important part 
of the volume, and the one on which its merits and demerits will 
ultimately be assessed. Here Mr. Massee is seen at his best, and 
here we have incorporated the results of the long and close attention 
he has given to the group, both in the herbarium and in the field. 
As to herbarium specime ns, he admits that he has enjoyed unusual 
e d to 
thoroughly critical. In the matter of classification he has adopted 
an arrangement which appears to have the advantage of being at 
once more natural and more practical than those previously pub- 
lished, and at the same time embodies the views he entertains of the 
phylogeny of the various divisions of the group. In framing these 
to arrange all the known forms in four orders, viz., Feritrichee, 
Columellifere, Lithodermee, and Calotrichee, all of w a are care- 
fully defined and distinguished before being separately dealt with. 
It will be noticed, however,. that he excludes not only Van Tieghem’s 
Acrasiee and Cienkowski’s Monadinee, but also the genus Ceratium, 
which is sometimes made the representative of an exosporous 
division of the group. Of the thoroughness with which the defi- 
nitions of the genera and species have been revised and amended, 
and the care with which the diagnostic characters are indicated, it is 
scarcely possible to speak too highly, as almost every page bears 
testimony to much conscientious and painstaking work in this 
direction. As they stand, the definitions are unquestionably the 
fullest and most precise yet offered to British students, and as they 
are at the same time very definite and direct, they may be regarded 
as doing all that words can do to mark and delimit the forms to 
which they apply. It is not the author’s fault that in these defi- 
nitions characters which are only visible under high microscopic 
powers hold a prominent place, for in the present state of 
knowledge this is inevitable. As he himself puts it, ‘When we are 
June 1892. 
