526 GEOFFREY SMITH. 
In this manner it would appear that the “knee-joint” in 
Peracarida and Eucarida is homologous, while a different 
seoment has been suppressed in each case, in the Peracarida 
the terminal segment, and in the Hucarida the second 
seoment from the body, which has fused with the third. 
Hansen has suggested that the claw usually present on the 
terminal joint of the Peracaridan limb represents the lost 
TEXT-FIG. 35. 
First thoracic appendage of Nyctiphanes. 
terminal segment, and this may possibly be the case, though 
a theoretical refinement of this nature must always remain 
doubtful. 
However this may be, the Anaspidacean limb with its 
eight segments gives us the generalised condition from 
which the Peracaridan and Hucaridan types can be easily 
deduced. 
