570 CAROLINE B. THOMPSON 



group I; in the presence of three zones of cells instead of the 

 four found in ants; in the incomplete differentiation of the two 

 lobes, whose cells are not separated by a deep furrow, as in ants, 

 and whose two cups or calyces are completely fused by inter- 

 vening masses of gha cells; in the shallowness of the cups; finally, 

 in the smaller size of the entire mushroom bodies and their sUght 

 differentiation in the different castes. 



IV. The central body 



The central body is situated in the central frontal plane of 

 the protocerebral lobes, embedded in their fibrous core, directly 

 beneath the intercerebral region. In form as well as in' position 

 the central body of L. flavipes resembles that of bees and ants. 

 It has two parts (fig. 15, c.b.), a curved dorsal portion, composed 

 of fiber bundles that are radially arranged with intervening 

 spaces, and a flatter ventral part, also fibrous. No nerve cells 

 are found within the central body, as in ants, where small nerve 

 cells occupy the spaces between the radial bundles of fibers, but 

 a few scattered nerve cells are occasionally found along the outer 

 surface. 



The structure of the central body is the same in all the castes, 

 but the size vanes with the size of the different brains (figs. 15, 

 22, 25). 



Lying beneath the central body are two small round bodies 

 which were formerly known as the 'tubercles of the central 

 body" and also as 'ocellar glomeruli.' I have shown, Thompson 

 ('12, '14), that in ants and in the bumble bee these previously 

 misinterpreted bodies are the posterior roots of the mushroom 

 bodies. In L. flavipes these rounded bodies are in connection 

 with the central body roots of the mushroom bodies (figs. 15, 

 16, c.b.r.), which, it will be remembered, arise from the distal 

 ends of the stalks in close proximity to the posterior roots. 



V. Ocelli and ocellar nerves 



Two simple eyes or ocelli are present in the adults and nymphs 

 of the sexual forms, and are situated on the lateral surfaces of 

 the head, in front of the compound eyes and behind the antennae. 



