188 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
irregularity in the retention. The time that each crab was under 
the microscope had to be very limited and the dimensions given do 
not represent measurements, but are based on comparisons with the 
unaltered pleopods of the left side. 
Class A. 
Rudiments without joints or rami. Twenty-five combinations, 
but only a few common to several specimens, viz .: — 
Ru, 
R, R, R : Ru, 
o, 
0, 
0, 
9 
examples. 
All series. 
Ru, 
R, R, R : Ru, 
Ru, 
0, 
0, 
8 
a 
All series excepting 
indifferent. 
Ru, 
R, R, R : Ru, 
Ru, 
Ru, 
Ru—, 
12 
a 
Naked series only. 
Ru, 
R, R, R : Ru, 
Ru, 
Ru, 
Ru, 
14 
ll 
All series. . 
Ru-f-, R, R, R : Ru-|-, Ru-f, Ru+, Ru-f, 13 “ Naked and indiffer¬ 
ent only. 
Class B. 
Rudiments without joints or rami. The variations of this class 
are probably only the result of defective ecdysis or injury during the 
glaucothoe stage. Three examples. 
Ru-)-, Ru-f, Ru-f, Ru-f : Ru, Ru, Ru, Ru, 1 example. Normal series. 
0, R, R, R : 0, O, O, Ru, 1 u Sinistral series. 
Ru-f, Ru-f, Ru-f, Ru-f : Ru-f, Ru-f, Ru, Ru, 1 “ Indifferent series. 
Class C. 
9 
Rudiments without joints or rami except once, where the append¬ 
age was small, but perfectly formed and of male type (R*). Eleven 
examples in all. 
Ru, R, R, R : Ru, 0, Ru, 
Ru, 
1 example. 
Normal series. 
Ru, R, R, R : Ru, Ru, R, 
0, 
1 
« * 
ll ll 
Ru, R, R, R : 0, Ru-f, (3, 
0. 
1 
a 
ll ll 
Ru, R, R, R : Ru, 0, Ru—, 
0, 
1 
a 
Sinistral series. 
Ru, R, It, R : 0, 0, Ru, 
0 , 
1 
a 
ii a 
Ru. R, R, R : (3, Ru—, Ru—, 
0, 
3 
it 
Naked and sinistral series. 
Ru, R, R, R : Ru, Ru-f, Ru, 
0 , 
1 
ti 
Naked series. 
Ru, R, R, It : 0, 0, ' R* 
o, 
1 
it 
Sinistral series. 
Ru, It, R, R:0, Ru-f, Ru, 
R, 
1 
u 
Naked series. 
