692 MR. P. R. AWATI ON THE MECHANISM 
cardo and stipes of the maxille and the other to the maxillary 
stylet. (iii.) The protractor muscles of the mandibles are attached 
to the levers and not to the mandibles. 
Labrum. 
This is the least disputed structure. Its homology with the 
labrum of the mandibulate insects has been determined with 
certainty. It is not, however, one of the appendages of the head 
but a continuation of the clypeal sclerite, from which it is not 
easily to be distinguished externally. 
Tue Morro tocy or tHE Heap. (Text-fig. 1.) 
The head of Lygus pabulinus consists of the following parts :— 
(1) The Epicraniwm.—tThis lies between the two large eyes. 
It is continued into 
(2) The Clypeus. (The frons, the intermediate portion between 
Text-figure 1. 
Lygus pabulinus. 
Mount of the whole head, macerated in potash (10 per cent.), and stained with 
saturated picric in 90 per cent. alcohol; showing the internal chitinous 
structures. Ob. 3 & Oc. 4. 
The lines numbered 2, 4, 5 indicate the planes of the longitudinal sections 
shown in the corresponding figures. 
