624 Mr. J. O. Westwood on the Paussidce, 



base of the part which Afzelius terms the gula triangularis, — to 

 consider that part, which Latreille has not noticed, as the 

 representative of the mentum, and consequentl)^ the " dents 

 laterales" of Latreille, or the external palpi of Afzelius, as the 

 produced anterior angles of the mentum ; 1st, from the evident 

 analogy between it and the mentum of Pentaplatarthrus and 

 Flatyrhopalus ; 2ndly, because Latreille himself has shown 

 that the mentum is not always articulated at the base, as in 

 Siagona, which he describes in the Genera Crustaceorum, ^c. 

 vol. iv. p. 208. as " sutur^ nulM basilari et processu paginae 

 inferae capitis efFormatum;" Srdly, because the labial palpi 

 arise between it and the true lip, which appears to be the 

 true typical structure of the Coleoptera ; and 4thly, because the 

 maxillae arise at the outer sides of the produced spines and 

 within the mouth ; in which respect this formation also agrees 

 with the typical structure of the Coleoptera, where the base of 

 the maxillae arises at the outer sides of the mentum ; whereas 

 in Catogenus, Passandra, Megagnathus, ^c. the maxillae arise 

 within or between the produced lobes or spines. 



As to the " dent intermediaire" of the labium mentioned by 

 Latreille, it appears from the observations of Afzelius, that it is 

 not a constant generic character ; its examination, however, in 

 the various species is rendered more difficult in consequence of 

 the peculiar arched formation of the maxillary palpi described 

 by Latreille as above. 



The labial palpi are generally bent backwards, although, as 

 may be observed from Afzelius's figures, they are occasionally 

 stretched forward ; in which latter case they fill up the space 

 formed by the arch of the maxillary palpi, and almost entirely 

 conceal the lip. 



The paucity of joints in the antennae, and their comparatively 

 immense size, are circumstances well worthy the attention of 



the 



