862 PROFESSOR E. RAY LANKESTER. 
fications is seen in Limnetis, where the distal lobe of the 
flabellum becomes polyarthrous (woodcut, fig. 1, XZX, d). 
The interest of this modification consists in the fact that it 
lends some support to the identification of the flabellum of 
the Phyllopoda with the polyarthrous ramus termed ‘ exopo- 
dite’ in the Decapoda. On other grounds I am led to doubt 
the correctness of this identification, as explained below. 
The fourth, fifth, and sixth endites in the same appendage 
of Limnetis are elongated, whilst the first, second, and third — 
are short and jaw-like. The tendency of the flabellum to 
elongate itself in the direction parallel with the long axis of 
the corm is remarkable, and tends to its separation into a 
distal and a proximal lobe. 
It is an important fact, which space does not allow me to 
further illustrate here, that the number of apophyses (both 
endites and exites), with the exceptional presence of an ad- 
ditional exite, is constant in the truncal appendages of all 
the Phyllopoda. 
The przoral and oral appendages are very variously 
modified. 
In order to determine further the homologies of the parts 
of the Crustacean limb it becomes important to ascertain 
what relation the parts of the foliaceous truncal appendages 
of the Phyllopoda have to the typical biramose appendages 
of a Nauplius. 
The investigations of Zaddach, and more especially of 
Claus, on the development of Apus furnish data for this 
determination. The limbs present in the Nauplius larva of 
Apus aud Branchipus persist in their primitive form at a 
time when the thoracic appendages have attained to a size 
nearly equal to theirs, and the comparison of the first 
and second thoracic foot (woodcut, fig. 1, XVI) with the 
biramose second pair of antenne (same figure, XVJIJ) 
leaves little room for doubt as to the homologous parts. The 
Nauplius biramose appendage is devoid of flabellum and of 
bract; it has, in fact, no exites. Its terminal segment 
(outer ramus or exopodite) corresponds to the terminal 
endite of the thoracic foot (the sixth), and its inner ramus 
(endopodite) corresponds to the next endite of the thoracic 
foot or the fifth. Rudiments of two other endites are 
present in the second pair of Nauplian appendages of 
Apus. 
‘The identification thus indicated is not capable of any 
more convincing proof than that afforded by the general 
similarity of relations in the two appendages compared; 
aud when the extreme fluidity (if the expression may be 
