356 JOURNAL OF COMPARATIVE NEUROLOGY. 
almost on a level with the nerve root, then passes laterad to the * 
nerve. This tract does not decussate (fig. 12, Me. 7.) 
Minor Tegumentary Tract. This is a small tract which may 
easily be traced from the tegumentary nerve inwards (mesad) 
to near the meson. I have not been able to determine whether 
it terminates there or decussates to the other side (fig. 13, 
M2. T.) 
I have not been able to detect a commissure which is un- 
doubtedly related to this nerve. However, between the anten- 
nulary commissure and the roots of the antennulary nerve there 
is a narrow commissure or decussation, the fibers of which can 
be traced to the vicinity of the roots of the tegumentary nerve; 
but it has not been possible to detect any of the fibers entering 
the nerve. 
Tracts Related to the Antennary Nerve. It has been possi- 
ble to demonstrate four tracts that connect with this nerve; the 
antennary commissure, the major antennary tract, the minor 
antennary tract, and the antenno-mushroom tract. 
The Antennary Commissure arises from the cells of the ven- 
tral nidus and decussates to the nerve of the opposite side. 
Major Antennary Tract. This tract arises from the ventral 
nidus and passes outwards (laterad) to the nerve of the same 
side. 
Minor Antennary Tract. This tract passes from the latero- 
ventral nidus to the branch of the antennary nerve of the 
same side. : 
Antenno-mushroom Tract. This tract passes from the inner 
mushroom nidus to the nerve of the same side. 
Optico-olfactory Commuissure or fibrillar Arch. This is a 
large and conspicuous commissure which connects the portions 
of the brain that lie adjacent to the roots of the mushroom bodies 
(figs. 3, 6, 9, 27). This is the homologue of the fibrillar arch 
(Kenyon) of insects. 
MusHroom BopDIigs. 
The mushroom bodies are composed of two factors, cells 
and fiber tracts. The cells are minute bodies having small 
