168 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
with the moult.to the glaucothoe. It opens on the ventral face of 
the second maxilla and in form is a bent tube whose distal end 
extends toward the cephalothoracic cavity. These glands must be 
very important for the zoea before the development of the green 
glands with the fourth stage, and, despite the fact that the green 
glands have a lumen and are therefore presumably functional, in 
the latter period the shell glands are relatively longer than in the 
three earlier stages. 
Our knowledge of the development of the sexual system is very 
meager. A sixth-stage larva or a mature glaucothoe shows in the 
abdomen near the tip of the nephrosac two fusiform clusters of 
five or six cells (pi. 8, fig. 42, g\ pi. 10, fig. 63). These are readily 
identifiable as the sexual glands. Younger zoeae and glaucothoe 
have similar cells lying beneath the pericardial septum in the 
thorax (pi. 10, fig. 62). This position recalls the grouping of the 
sexual cells in the zoeae of Mysis, (Nusbaum, ’ 87 ), Palaemonetes 
(Allen, ’ 93 ) and Gebia (Butschinsky, ’ 94 ) the only Decapod larvae 
for which they have been described. I Avas not able to find sexual 
cells in any earlier stage than the fourth zoea, perhaps because of 
the thickness of my sections. These cells pass to the abdomen at 
the time when the livers shift, but unfortunately no sections slioAved 
them in transition. There must, hoAvever, be an increase in their 
number at this time. The pericardial group contains less than half 
a dozen cells, while the abdominal clusters have five or more cells 
apiece. 
The time for the appearance of sexual ducts and orifices is 
unknown. When adolescent larvae reach an age of about forty 
days from the glaucothoe, they, show Avhat are apparently sexual 
orifices. But if these specimens are sectioned, no openings can be 
found nor anything that can be interpreted as even the anlage of a 
duct. These “pseudo-orifices” must be merely shallow depressions 
in the integument over the regions where the true openings will 
ultimately be developed. The crabs collected at Wareham, in 
1900, which were certainly not less than one year old, had the 
sexual ducts well developed (pi. 9, fig. 53, scl), and the sexual 
glands were large and complexly coiled, but not quite mature. 
This would mean that the production of sexual products would not 
ha\ 7 e occurred in them before the folloAving year, i. e., the hermit 
crab is probably not mature before the second or third year of its 
life (see page 168). 
