Turner, Mushroom Bodies of the Crayfish. 367 
D, Ant.—Dorsal antennulary tract. 
D.N.—Dorsal nidus. 
D.L.7.—Dorso-lateral tract. 
A —Fibrillar arch. 
La. lb. Ic. Td.—Lower optic commissure, 
JI,D.£.—Inferior dorsal lobe. 
ZI.M,N.—Inner mushroom nidus. 
L. V.N,—ULatero-ventral nidus. 
M. Ant.—Major antennulary tract. 
M.7.—Major tegumentary tract. 
Me. 7T.—Mesal tegumentary tract. 
Mz. Ant.—Minor antennulary tract. 
O. A. T.—Optico-arch tract. 
O.C.—Optic chiasm. 
O. Com.— Oesophageal collar, 
O.M,N.— Outer mushroom nidus. 
O. M, Nv.—Oculo-motor nerve. 
O.M. T.—Optico-mushroom tract. 
O.N.—Optic nerve. 
Ol. L.—Olfactory lobe. 
Op.L,.—Optic lobe. 
£.B.—Procerebral bridge. 
P.£Z.—Pyriform lobe. 
S,M@.—Stalks of the mushroom-bodies. 
T.Z.—Tegumentary lobe. 
T.NV.—Tegumentary nerve. 
All figures were drawn with the camera lucida. 
Fig. 
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pillar. 
PLATE XxXI. 
z. Diagram showing the lobes, nidi and nerves of the crayfish brain. 
2-8, Transverse sections through the crayfish brain. 
PLATE XXII. 
g. Transverse section through the crayfish brain. 
ro-rg. Horizontal sections through the crayfish brain. 
75-17. Longitudinal ‘* bc ss oe cs 
PLATE XXIII. 
z8. Longitudinal section through the crayfish brain. 
7g. Origin of optic nerves of the crayfish. 
20, 22, 23. Sections through the mushroom bodies of the crayfish. 
24. Cluster of nerve cells from the crayfish. 
21, 25, Transverse sections through the crayfish brain. 
26. ee eg oF ‘¢ brain of the Cecropia cater- 
