446 



COMPARATIVE ANATOMY 



CHAP. 



1. The upper lip (labrum Ihr) is an uniDaired piece which covers 

 the oral aperture in front and from above, and has nothing to do with 

 the limbs. 



2. The Mandibles (upper jaws, md) consist on each side of a 

 powerful but unsegmented masticatory plate mth toothed edge. 



3. The anterior maxillae (lower jaw). Each of these 2 maxillae 

 consists of a 2-jointed basal portion {mx^, which carries first a 

 5-jointed feeler {pm, palpus maxillaris), and second, 2 unjointed 



Fig. 303.— Moutli parts of Blatta (Orthoptera, after Savigny). Ibr, Labrum (upper lip) -.Imd, 

 mandible; wmi, anterior pair of maxilla;; mx^, posterior pair of maxillje = lower lip (labium); st, 

 stipes (stem) ; m, mentum ; sm, submentuni ; mi and me, mala interna and externa, inner and outer 

 ridges of the 1st and 2d pairs of maxillie ; pm, palpus maxillaris, feeler of the anterior maxlllEe \ pi, 

 palpus labialis, feeler of the posterior maxillge. 



masticatory ridges, one outer {me, mala externa) and one inner {mi, 

 mala interna). 



4. The posterior maxillae together form the lower lip (labium, mo:^. 

 Each posterior maxilla consists of the same parts as the anterior 

 maxillse (basal part, 3-jointed feeler pi, outer and inner masticatory 

 ridges me and mi), but the 2 basal parts on each side have grown 

 together behind and below the mouth in the middle line. 



These mouth parts are adapted for biting and chewing. 



We shall now describe the most important modifications of the above type in 

 systematic order. 



