ON THE ANASPIDACEA, LIVING AND FOSSIL. 525 
the primitive Anaspidacean condition of these limbs is the 
possession of eight segments or joints, of which three are 
placed distally to the “knee” while five are placed proxi- 
mally (e.g. text-fig. 18). 
In the Peracarida and Hucarida we observe typically 
seven segments, but the ‘ knee” in the two divisions, as 
pointed out by Hansen (14), is in a different position. In the 
Peracarida (e.g. Mysidacea) (text-fig. 34) there are two 
TEXxtT-FIG. 34. 
First thoracic appendage (maxillipede) of Macromysis flexuosa. 
segments distal to the “knee,” and primitively five proximal 
to it; in the Eucarida there are three segments distal to the 
“knee” and four proximal to it (text-fig. 35). Now we 
have seen that in the Anaspidacea there is a tendency for 
the second and third segments to fuse, and this process carried 
to completion would give us the Eucaridan limb. In the 
Peracaridan limb we may suppose that a segment has dis- 
appeared distal to the knee, probably the terminal segment, 
which in the Anaspidacea is very small. 
