MORPHOLOGY OF THE SECOND M AXILLAE 69 



adopt this view it will greatly simplify our conception of the real 

 nature of this complicated organ. The object of the fusion of the 

 basal portion appears to be to form an under-lip, in order both to 

 prevent the food from falling backwards out of the mouth, and, with 

 the aid of the first pair of maxillae, to pass it forward to be crushed 

 between the mandibles, the two sets of appendages acting somewhat 

 as the tongue of vertebrates to carry and arrange or press the mor- 

 sels of. food between the teeth or cutting edges of the mandibles. 



The spines often present on the free inner edges of the first and 

 second maxillae (Figs. 54, 62) form rude combs which seem to clean 

 the antennae, etc., often aiding the tibial combs in this operation. 



The submentum and mentum, or the mentum when no submentum 

 is differentiated (with the gula, when present), appear to be collec- 

 tively homologous with the cardines of the first pair of maxillae, to- 

 gether with the palpifers and the stipites. 1 These pieces are more or 

 less square, and have a slightly marked median suture in Termitidae, 

 the sign of primitive fusion or coalescence. 



The most primitive form of the second maxillae occurs in the Or- 

 thoptera and in the Termitidae. The palpifer is either single (Peri- 

 planeta, Diapheromera, Gryllidae) or double (Blatta orientalis, Locusti- 

 dae). In Prisopus the single piece in front of the palpifer is in other 

 forms divided, each half (Blatta, Locustidae, Acrydidae) bearing the 

 two " paraglossae," which appendages in reality are the homologues 

 of the lacinia and galea of the first maxillae. 2 In the Termitidae (Fig. 

 65) the lingua is not differentiated from the palpifer, and the two 

 paraglossae (or the lamina externa and interim of some authors) 

 with the palpus are easily seen to be the homologues of the three 

 lobes of the first maxillae. In the Perlidae (Pteronarcys, Fig. 66) 

 the palpifer is divided, while the four paraglossae arise, as in Priso- 

 pus and Anisomorpha, from an undivided piece, the lingua not being 

 visible from without. In the Neuroptera the lingua or ligula is a 

 large, broad, single lobe, without " paraglossae," and the palpifer is 

 either single (Myrmeleon, Fig. 67), or divided (Mantispa, Fig. 68). 



1 After we had arrived at this conclusion, and written the above lines, we received 

 the Zoologischer Anzeiger for March 29, 1897, in which Dr. N. Le'ou publishes the same 

 view, stating that each side of the subraentum is the homologue of the cardo, and 

 each side of the mentum corresponds to the stipes of a single maxilla (p. 74) 



2 Miall and Denny were the first to homologize the paraglossa; with the galea and 

 laciuia, showing the complete resemblance of the second maxillae to the first pair, 

 remarking that " the homology of the labium with the first pair of maxillae is in no 

 other insects so distinct as in the Orthoptera." We have also independently arrived 

 at a similar conclusion, but believe that the mentum corresponds to the first max- 

 illary cardo, and the palpifer to the first maxillary stipes, the sclerite of each 

 maxilla being fused to form the base of the labium, i.e. the unpaired mentum 

 submentum. 



