A PROBLEM IN CLASSIFICATION 925 
The ingenious comparison instituted by Darwin between 
the Macruran Leucifer and the Cirripede Lepas is well 
known, and, as the illustrative figures have often been 
reproduced, the long neck, the projecting eyes, and feeble 
limbs of Leucifer are comparatively familiar. The petasma, 
or curtain, at the first pleopods of the male, is in this 
genus a very conspicuous object. 
Schizopoda. 
Spence Bate regards the Schizopods as an aberrant 
group of his Macrura dendrobranchiata, and urges that, 
‘with the exception of the variable condition of the pereio- 
poda, the several genera do not possess a single character 
that is not held in common with some genus of the 
Macrura.’ Without any wish to pronounce upon the 
validity of the arguments and facts which he adduces in 
support of his view, I must here simply follow the dictates 
of convenience, and leave the Schizopoda to be treated 
later on as a separate sub-order. 
