252 



ptilota: imago — external anatomy 



Fifjs. 99, Maxilla of the great 

 pirriis) seen from abo%c— 

 from the back. 



water-beetle [Ht/droiis 

 100, from below— lUl, 



Maxillce, or lower jaws {yax in the figures). — These organs 

 are two in number, and are placed beneath the mandibles, 



from which they differ 

 in their less firm con- 

 sistence and more com- 

 plicated structure, be- 

 ing formed of several 

 parts, and especially by 

 the possession of a slen- 

 der articulated appen- 

 dage or palpus, attach- 

 ed to each. They ap- 

 pear to be more espe- 

 cially connected with 

 the lower lip, serving, in some instances, as a sheath for its 

 defence ; in the beetles, however, they are generally quite 

 detached. In a table of the comparative variation of the 

 chief insect organs, Mr. MacLeay has shown that the maxillae 

 are less liable to vary than any other ; hence it is important 

 to note the modifications to which they are subject. 



The maxillae appear typically to consist of five pieces, ex- 

 clusive of the maxillary palpi ; at least, those maxillae which 

 are the most complicated in their structm-e exhibit this 

 number of parts. They are the cardo or hinge (figs. 99, 100, 

 101 a), a most appropriate term, designating a transverse 

 horny piece by which the jaw is affixed within the mouth 

 by membranes. Strauss calls this the hranche transversale, 

 Savigny the support, Burmeister the base, and Newman the 

 insertio. This piece is especially distinct in beetles and bees. 

 The tv.o following pieces {b and c) are closely soldered to- 

 gether, and compose the horny pillar between the basal 

 hinge and the terminal lobes. Of these two parts, the ex- 

 ternal portion (c), as f^rst noticed by Latreille, and since 

 named la piece palpi/ere by Strauss, and the squama by 



