580 CAROLINE B. THOMPSON 



end of the frontal gland is prolonged into a slender median 

 process that passes downward posterior to the protocerebrum 

 and connects the frontal gland with the great tentorial mem- 

 brane that divides the interior of the head into the two parts 

 in which lie the supra- and the subesophageal ganglia, and 

 through which the ventral connectives pass. The basement 

 membrane is similar in structure in all the castes. 



Muscle fibers may be seen attached to the posterior or caudal 

 surface of the basement membrane in the true adult, in surface 

 \'iews, but I have not observed them in either of the nymphs; 

 muscle fibers are also attached to the basement membrane in 

 the soldier and in the worker. 



The fontanel nerve (figs. 2, 19, 23, 26, f.n.) is the slender un- 

 paired nerve which makes its exit through apertures of the 

 median ventral process of the basement membrane of the frontal 

 gland, and which passes vertically downward and enters the 

 median dorsal surface of the protocerebral lobes at a definite 

 point, namely: between the large posterior roots of the mush- 

 room bodies and in the same frontal plane in which the ocellar 

 nerves enter the protocerebral fibrous core. This is the first 

 tim.e that this nerve has been described or figured in any termite 

 brain. It is present in a similar position in all the castes and 

 phases of L. flavipes that have been examined, and it is undoubt- 

 edly a strand of nerve fibers, although a very delicate one. I 

 have provisionally termed this nerve the fontanel nerve, and we 

 shall return to it again after a discussion of the frontal gland in 

 the other castes. 



2. The true adult. I have not yet succeeded in making good 

 sections of the true adult's frontal gland, but in a surface view 

 of an entire brain and frontal gland dissected out and mounted 

 it is most evident that the inner surface of the frontal gland is 

 lined with a wavy chitinous cuticula, the channels of which 

 converge toward the anterior opening on the surface of the head. 



Although I have unfortunately not studied the true adult 

 frontal gland in sections and can not therefore describe the epi- 

 thelial cells, the facts that it is larger than in the nymph with 

 long wing pads, and that it has acquired a chitinous cuticula. 



