256 Annals Entomological Society of America [Vol. IV, 



PLATE XV. 

 A series of four photographs of cross sections through the 1st thoracic ganglion 

 of Corydalis through a caudal level. The last figure is through the more central 

 portion of the ganglion. Nerve cells show at the sides. The central fibrous mass 

 is shown in all, and longitudinal fibers can be traced. In the last three figures 

 cross commissures may be seen. The dark mass at the left or ventral side is part 

 of the surrounding tissues and not a part of the ganglion. x60. 



PLATE XVI. 

 Fig. 1. Photograph of a cross section parallel with the long axis of the brain 

 through its central region. One half only shown. The dorsal side is up. The 

 optic nerve is the swelling off at the right above, while leading off below is the 

 broad crus. The dorsal masses of cells show, also central fibers and the stalk and 

 root of the mushroom body. x75. 



Fig. 2. A similar photograph from the same series cut farther one side, 

 cephalad. x75. 



Fig. 3. Photographs of the larger cavity shown in Figs. 1 and 2. x250. 



Fig. 4. Section of the brain cut in a similar way as Figs. 1 and 2, but farther 

 cephalad. The ventral side is at the left. The dorsal to the right. x75. 



Fig. 5. Longitudinal section of the sub-esophageal ganglion. Above the first 

 branch to the left is one of the crura cerebri, the next it is the mandibular. Below 

 the branch cut only through its edge is one of the ventral connectives. x75. 



