CASTES OF TERMOPSIS 



503 



shape of thorax ah-eady mentioned, are the relatively broader 

 head and the smaller lateral tibial spines of the younger nymphs. 



The most interesting features of the internal anatomy are in the 

 nervous system — brain, eyes, and frontal gland — and in the 

 digestive and reproductive systems. 



The brain of Termopsis has the form characteristic of the lower 

 termites, namely, a great extension from side to side, caused by 

 the size and lateral position of the optic lobes, and the sHghter 



Fig. 3 Termopsis angusticollis, a comparison of the metathoracic legs of the 

 four castes, a, first-form adult; 6, mature first-form nymph; c, immature first- 

 form nymph; d, second-form adult; e, /, third-form adults; g, h, adult soldiers. 

 Spencer oc. 6, obj . 32 mm., stage level, reduced three-fifths. 



development of the mushroom bodies. The smaller mushroom 

 bodies of lower termites with their smoother rounded surfaces 

 may be recognized at a glance from the relatively larger and con- 

 voluted bodies of a higher termite, e.g., Reticulitermes. 



As in other termites, the brain of Termopsis attains its greatest 

 size and complexity in the mature nymph and young adult of the 

 first form, these two phases being practically alike in brain 

 structure. Figure 4, a, represents an optical section of the brain 

 of a first-form adult; the huge optic lobes are correlated with the 



