THE MOUTH-PARTS OF THE THYSANOPTEKA. 27 



But if this is a mandible, what are the styliform organs 

 which have always been considered the mandibles of Thy- 

 sanoptera? Two symmetrically developed organs of this 

 kind are always present. They do not, however, consist 

 of one chitinous segment, as commonly represented, but 

 the styliform portion is articulated (rnovably, I think) 

 at its base with a shorter piece, which by ordinary dissec- 

 tion comes free with the other. In dissections made with 

 greater care these basal pieces are seen to be joined to 

 the bases of the palpus-bearing triangular parts. It seems 

 probable therefore that the styliform organs are lobes of 

 the maxillae, and that the triangular organs are also lobes 

 of the same. The fact that the palpi are borne upon the 

 triangular parts would indicate that these latter were the 

 galese, and the more slender ones were lacinise. But I 

 am not satisfied with my examination of these parts, and 

 do not wish to insist at present on more than the proba- 

 bility that they are lobes of the maxillae. In position, the 

 styliform parts lie above or below the palpus-bearing 

 pieces, according to the side from which they are seen, 

 and their distal portions pass between the rims at the ends 

 of the latter. When dissected free from the other mouth- 

 parts, and placed under a cover glass, they appear as rep- 

 resented in the figure, the slender pieces being pressed to 

 the outside. 



