A CENSUS OF LEG-JOINTS 43 
though it has been strongly urged that one and the same 
term ought to be applied to homologous parts throughout 
the whole crustacean class, either nature has opposed the 
rigid application of such a system, or the wit of man has 
not yet been able to devise appropriate terms. 
It may here be mentioned that the full number of 
joints for a malacostracan trunk-leg is seven. With a view 
to uniformity of nomenclature, the afflicted naturalist has 
for many years had to deal with these seven under the 
following names :—Coxa, basis, ischium, merus, carpus, 
propodus, dactylus, which respectively signify hip, foot, 
socket of thigh joint, thigh joint, wrist, forefoot, and 
finger or toe. Originally the names were longer, all being 
podites, from coxopodite to dactylopodite, to the use of 
which the philosophic French still adhere, though the 
time-saving Anglo-Saxon has for the most part rejected 
them. Among other difficulties in this terminology under 
either form, it has to be remembered that the basis is the 
second, not the basal joint of the limb. ‘The more reason- 
able plan is now being widely followed of naming these 
joints simply according to their numerical order, the coxa 
being called the first joint, and the dactylus the seventh. 
But the older names have still to be borne in mind by 
those who study the older literature. Even the numbers 
are attended by a very unfortunate element of confusion. 
The late Axel Boeck, when introducing the use of num- 
bered joints, was studying the Amphipoda, in which the 
first joint of a leg is seldom, if ever, free. Taking into 
account, therefore, only the six free joints, he called the 
second joint the first, and made the finger the sixth, instead 
of seventh. In treating separately of the Amphipoda or 
Isopoda, many naturalists have followed Boeck’s usage as 
reasonable and convenient. But when other Crustacea are 
considered in which an appendage has the first joint or 
perhaps all the seven joints free, they must be numbered 
from one to seven, and whenever a comparison is needed 
between the limbs of the Edriophthalma and those in 
other groups, two different systems of numbering the 
joints cannot fail to be highly embarrassing. It must 
