548 ASELLIDA. 
and 8, the embryo is now nearly arrived at its full 
development, the legs exhibiting traces of articulation, 
and the lateral appendages having lost their trilobed ap- 
pearance; the mandibles, two pairs of maxillz, foot- 
jaws, and branchial plates, and the terminal appendages 
of the tail are visible in figure 8; lastly, in figure 9, 
the embryo is seen in its final stage, with the large 
lateral antennz articulated, and the lateral appendages 
entirely lost. In figures 6 and 9 it will be observed 
that there are only six leg-bearing segments, and six rudi- 
mental pairs of legs, whilst there are seven segments and 
as many pairs of legs in the fully developed animal; 
Rathke affirming that ‘le dernier de ces anneaux et 
sa paire de pattes ne se forment qu’en peu de tems aprés 
la sortie du jeune de la cavité incubatoire” of the 
mother; he, however, asserts that the wanting seventh 
segment is produced by the division into two parts of 
the sixth segment before the first moulting of the ani- 
mal, but admits that the formation of this last pair of 
legs ‘‘m’est restée assez obscure,” partly because it is 
effected very rapidly, and partly because the other legs, 
being long, cover all the hind parts of the body.* 
We have ourselves examined the earliest stages of 
these animals, and our observations agree with those of 
Rathke, except that in the early embryonic condition 
the lateral appendages appeared to us to be entire, with 
a rounded terminal knob, instead of being tripartite, and 
that in the state corresponding with that of our lower 
right-hand figure, the upper pair of antenne are free, 
as in figure 9, and that the external sac-like appendages 
were associated with the hepatic lobes. 
* This circumstance is of considerable importance, viewed in connection with 
the question of the number of legs in the early stages of Entoniscus and 
Cryptothiria (Liriope). 
