STUDIES ON THE NERVOUS SYSTEM OF ORUSTACEA. 475 
fibre takes a slightly curved course outwards and downwards, 
to pass from the cord by the anterior root. It gives off three 
or four small branches to the neuropile. The element stained 
in Th. V—X. Inserted in fig. 1 in Th. V, VII, VIII, and X. 
J. Type: the red element passing through the 
posterior root in Th. VII. 
The fibre of this element has a somewhat curious course. It 
starts from a very small cell in the median mass, runs for some 
distance outwards, and then takes a circular course through 
the neuropile, forming a complete loop, after which it passes 
outwards to the posterior root. From the upper margin of the 
loop three branches are given off, whilst from its lateral side a 
straight arm passes inwards and meets a similar arm from the 
opposite side. <A direct fusion of the two arms has, however, 
never been observed. This element has stained in Th. VII 
-—IX, and is inserted in each case in the figure. 
K, 
This element has been satisfactorily demonstrated up to the 
present only in Th. III. The cell lies in the median ventral 
mass, and from it the fibre passes outwards for a considerable 
distance, then suddenly turns and runs inward until it crosses 
its fellow of the opposite side, from which point it continues 
its former direction till it passes out at the posterior root of 
the ganglion, on the opposite side to that upon which the cell 
lies. This element differs, therefore, from the elements pre- 
viously described in the fact that fibres of opposite sides de- 
cussate, 
L. 
This is an element in Th. I, and is coloured red in the figure. 
The cell lies near the median mass. The fibre passes back- 
wards and slightly outwards, then turns upwards and passes 
out at the anterior root. A branch is given off at the point 
where the fibre turns, which soon bifurcates, one branch run- 
ning backwards, whilst the second runs transversely to the 
opposite side of the ganglion. 
