156 



TURNER. 



[Vol. II. 



be homologized directly with them. In neither Retzius' figure 

 of the brain of Astacus fluviatalis, nor in Bet he's figures of the 

 brain of Carcinns moenus, can I find cells having the relations 

 and the appearance of those I find in the bee. 1 have noticed 



c.-yn. 



Fig. I. — Section through the mushroom bodies of Cecropia larva 



nothing resembling the structures in Isopods or Amphipods, nor 

 have I found indications of them in the brains of Pauropus, 

 Polyxeniis, Scolopcndrclla, Lithobins, nor even in several forms 

 of TJiysanura that I have examined. If cells homologous with 

 those filling the cup-like calyx of the mushroom bodies of the 

 bee are at all present in these forms, they are so undifferen- 

 tiated as to be indistinguishable from the general mass of cells 

 about them." 



More recently Hamaker ^ has homologized certain groups of 

 cells found in the brain of Nereis with the Hexapod mushroom 



S.in 



Fig. 2. — Section through the brain of Cambarus. 



bodies. He bases this conclusion upon the following facts : 

 (i) the cells of that type are confined to the brain; (2) they 



1 Hamaker, J. J., "The Nervous System of N'ereis vireiis Sars," Bull. Mas. 

 of Comp. Zool. at Harvard College. Vol. xxxii, No. 6. 1898. 



