510 
W. T. CAL MAN. 
There can, therefore, be no question as to the desirability of 
recognising the three families Anaspididm, Koonungidae, 
and Bathynellidae. When, however, we attempt to define 
more closely the relationships between these families, and 
especially when we try to frame a scheme of classification to 
include the fossil genera as well, the matter becomes much 
more complicated. 
The attractive simplicity of a dichotomous classification is 
always less easy to escape from and more likely to be mis- 
leading when the forms to be classified are few and the' 
characters available for their discrimination are scanty. 
Such dichotomies have more than once proved a snare to the 
taxonomist of Crustacea 1 and they have already made their 
appearance in the attempts to classify the Syncarida. Thus 
Chappuis, in his preliminary paper on Bathynella (1914a, 
p. 47) proposed to divide the members of the group into 
Pleopodophora and Apleopodophora 2 according as they possess 
a full or a reduced series of abdominal appendages. In his 
later paper (1915, p. 172) at my suggestion, he based his 
division on the freedom or coalescence of the first thoracic 
somite, naming the groups Bathynellacea and Anaspidacea. 
Still more recently Vanlioffen (1916) 3 has separated the 
genera that possess thoracic exopodites from the fossil genera 
in which these appendages have not yet been discovered, 
opposing the new name Duplicipoda to FritsclTs Simplicipoda. 
It would be difficult, perhaps, to find a basis of classification 
with less to commend it than that selected by Dr. Van- 
lioffen. 
1 We need only recall the false antitheses of Entomostraca and 
Malacostraca, Phyllopoda and Cladocera, Edriophthalma and Podopli- 
thalma, Macrura and Brachyura. In each of these cases one of the 
paired groups has proved, on closer examination, to be a heterogeneous 
assemblage. 
2 Giving, by accident or by design, to the division that excludes 
Bathynella the group-name originally devised by Vejdovsky (1899) 
for Bathynella alone. 
3 I am again indebted to M. Chappuis for the loan of Dr. Vanhoffen’s 
pamphlet. 
