44 



AN INTRODUCTION TO ENTOMOLOGY 



or superior lobe, and the digitus or finger. The maxilla may also bear claw-like 

 or tooth-like projections, spines, bristles, and hairs. 



In the following description of the parts of the maxillae, only very general 

 statements can be made. Not only is there an infinite variation in the form of 

 these parts, but the same part may have a very different outline on the dorsal 

 aspect of the maxilla from what it has on the ventral. Compare Fig. 55 and Fig. 

 56, which represent the two aspects of the maxilla of Hydrophilus. Excepting 

 Fig. 56, the figures of maxillas represent the ventral aspect of this organ. 



The cardo or hinge (a) is the first or proximal part of the maxilla. It is usually 

 more or less triangular in outline, and is the part upon which nearly all of the 

 motions of this organ depend In many cases, however, it is not the only part 

 directly joined to the body ; for frequently muscles extend direct to the aibgalea, 

 without passing through the cardo. 



The stipes or footstalk (&) is the part next in order proceeding distad. It is 

 usually triangular, and articulates with the cardo by its base, with the palpifer 

 by its lateral margin, and with the subgalea by its mesal side. In many insects 

 the stipes is united with the subgalea, and the two form the larger portion of the 

 body of the maxilla (Fig. 53). The stipes has no appendages; but the palipfer 

 on the one ide, and the subgalea on the other, may become united to the stipes 

 without anys trace of suture remaining, and their appendages will then appear 

 to be borne by the stipes. Thus in Fig. 53 it appears to be the stipes that bears 

 the galea, and that receives muscles from the body. 



The palpifer or palpus-bearer (c} is situated upon the lateral (outer) side 



of the stipes; it does not, 

 however, extend to the base 

 of this organ, and frequently 

 projects distad beyond it. 

 It is often much more 

 developed on the dorsal 

 side of the maxilla than on 

 the ventral (Figs. 55 and 56). 

 It can bereadily distinguished 

 when it is distinct by the 

 insertion upon it of the ap- 

 pendage which gives to it 

 its name. 



The maxillary palpus or 

 feeler (<f) is the most conspicuous of the appendages of the maxilla. It is an 

 organ composed of from one to six freely movable segments, and is articulated 

 to the palpifer on the latero-distal angle of the body of the maxilla. 



The subgalea or helmet-bearer (e) when developed as a distinct sclerite is most 

 easily distinguished as the one that bears the galea. It bounds the stipes more 

 or less completely on its mesal (inner) side, and is often directly connected 

 with the body by muscles. In many Coleoptera it is closely united to the 

 lacinia; this gives the lacinia the appearance of bearing the galea, and of being 

 connected with the body (Fig. 56). In several orders the subgalea is united to 

 the stipes; consequently in these orders the stipes appears to bear the galea, 

 and to be joined directly to the body if any part besides the cardo is so 

 connected. 



Fig. 55- Ventral as- 

 pect of a maxilla of 

 Hydrophilus. 



Fig. 56. Dorsal as- 

 pect of a maxilla of 

 Hydrophilus. 



