r)7() CAROLINE B. THOMPSON 



and the ventral surface of the protocerebral lobes, also the un- 

 paired recurrent nerve which arises from the posterior surface 

 of the frontal ganghon. This latter nerve (figs. 14 to 26, r.n.) 

 mns backward above the esophagus into the thorax and at a 

 short distance posterior to the supraesophageal ganglion expands 

 into the socalled 'esophageal ganglion.' 



X. The ventral connectives and the subesophageal ganglion 



The two slender ventral connectives (fig. 2, v.c.) arise from the 

 posterior surface of the tritocer. bral commissure. They con- 

 tinue backward side by side, their inner surfaces touching, 

 beneath the esophagus and above the bread tentorial band of 

 chitin that is present in the interior of the head. They become 

 still smaller, and pass down through the tentorial aperture, 

 finally merging into the dorsal surface of the subesophageal 

 ganglion. 



The subesophageal ganglion (fig. 2, sb.g.) is large and consists 

 of a fibrous core and a thick investing layer of nerve cells on 

 the ventral surface. From the anterior end arise the mandibu- 

 lar nerves, md.n., from the posterior end, the maxillary, mx.n., 

 and the labial, Ib.n., nerves. The branches of these nerves, 

 described by Holmgren, have not been traced. Immediately 

 behind the point of exit of the labial nerves the subesophageal 

 ganglion ends, or rather is continued into the thoracic connec- 

 tives, which pass upward and out of the head through the great 

 tentorial aperture. 



XL The frontal or fontanel gland and the fontanel nerve 



The frontal or fontanel gland of the termites has long been 

 an object of much interest and speculation. It is situated in 

 the median line of the frontal surface of the head beneath the 

 so-called 'fontanel,' which is defined by Brues ('15) as "sl small, 

 depressed pale spot on the front of the head between the eyes 

 (isoptera)." 



In surface views of the heads of the castes of L. flavipes, 

 (figs. 8 to 12) the frontal gland appears as a rather triangular or 

 rounded mass lying in the space between the two mushroom 

 bodies. In the adult sexual forms and in the soldier a tiny round 



