526 CAROLINE BURLING THOMPSON 



The antennary lobes, a.L, lie ventral to the protocerebral lobes, 

 and some of the antennary nerves issue at this point. The four 

 branches of the ocellar nerves, o.n., are seen outside the brain 

 sheath, above the pars intercerebralis, the space between the 

 mushroom bodies. The esophagus, oe., with the recurrent nerve, 

 r.n., above it, lies between the antennary lobes. 



In figure 11 the protocerebral lobes are deeply indented for a 

 short distance, about five sections, and the space is filled with 

 small nerve cells and with axons from large cells in the inter- 

 cerebral region. The nerves from the ocelli have entered the 

 brain and form the four ocellar lobes, oc.l. The anterior parts of 

 the optic lobes have appeared, and the double roots of the labro- 

 frontal nerves, l.f.n., make their exit from the antennary lobes. 



Figure 12 shows that the previously solid fibrous core becomes 

 separated in the mid-dorsal region into bundles of fibers running 

 from side to side in front of and between the stalks of the mush- 

 room bodies. These fibers are the anterior part of a commissure 

 which in this paper will be termed the ''anterior dorsal commissure, 

 a.cm., and which will be described in more detail under the head- 

 ing of the protocerebral commissures. The stalks of the mush- 

 room bodies, st., penetrate deep into the fibrous core but never 

 meet in the mid-line, remaining always separated by a narrow 

 space. The optic nerves enter the optic lobes, o.l., both in this 

 and in the preceding section. 



Figure 13 shows that the dorsal and median part of the pro- 

 tocerebral lobes has disappeared except for the slender anterior 

 commissure, a.cm., which passes in front of the mushroom body 

 stalks above the central body, c.h., connecting the lateral proto- 

 cerebral lobes. These are also united by a narrow tract of fibers 

 lying above the esophagus but below the mushroom body stalks. 

 The three parts of the optic lobes, outer, middle, and inner fiber 

 masses, are clearly shown, o.f., m.f., i.f.; the ocellar lobes have 

 increased in size and lie near together, the outer lobes, from the 

 lateral ocelli, are larger than the inner lobes, from the anterior 

 ocellus. Fibers connect the central body, c.b., with the lateral 

 protocerebral lobes. 



