158 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
glaucothoe (pi. 4, fig. 6). With the seventh stage, however, the 
longicarpus young become separable from annulipes larvae, as in 
them the brown bands are lost. The full adult colors and the com¬ 
plete specific form are not attained until about the twentieth day 
from the glaucothoe. The sixth stage also has a nine-jointed 
antennal flagellum and certain retrogressive alterations in the 
mouth parts, which are legacies from the glaucothoe (pi. 5, figs. 10, 
12, 13). The elongation of the flagellum is very gradual, the 
nine-jointed condition often persisting till the eighth stage, while 
crabs forty days from the glaucothoe have only 17 or 27 joints. 
The metamorphosis of the pleopods during this period is of special 
interest. At no time are there any traces of appendages on the 
peduncle, which is interesting when we remember that some Pagu- 
rids, as for example, Sympagurus and Paguristes, have pleopods on 
this segment in the adult. Typically, the sixth stage has no append¬ 
ages on the right side of the abdomen, except the uropod, but on the 
left the pleopods are well developed on segment three to five and are 
of the type found in the glaucothoe, i. e., they resemble those of the 
adult male. On the second segment the pleopod is reduced to a 
mere rudiment (pi. 4, fig. 6). About nineteen percent of reared 
sixth-stage larvae, however, retain rudiments of one or more of the 
right hand pleopods. The typical reduction may be expressed in a 
formula, by use of R for an appendage which is retained intact, Ru 
for a rudimentary appendage, and O to denote the loss of an 
appendage. The non-typical reductions are dealt with in another 
part of this paper. 
Glaucothoe. Sixth Stage. Adult Male. Adult Female. 
Left 
Right 
Left 
Right 
Left 
: Right 
Left 
: Right 
Seg. 1 O 
0 
0 
0 
0 
: 0 
0 
: 0 
“ 2 R 
R 
Ru 
0 
0 
: 0 
R 
: 0 
“ 3 R 
R 
R 
0 
R 
: 0 
R 
: 0 
“ 4 R 
R 
R 
0 
R 
: 0 
R 
: 0 
“ 5 R 
R 
R 
0 
R 
: 0 
R 
: 0 
“ 6 +R 
R — 
+R 
R — 
+R 
: R— 
+R 
: R— 
At the moult to the seventh stage or, more rarely, at the next 
following moult, the retained rudiments are lost, except the one on 
the second segment in those crabs which will become females. But 
although sex can be recognized thus early, not less than a year and 
