1879.1 doo [Horn. 



The clypeus normally is not broader than the head, the margin reflexed, 

 the anterior edge more or less arcuate, the angles rounded. In two species 

 the clypeus is wider than the head, in Wheeler i conspicuously so with the 

 angles rather acute, in crinitus less dilated with the angles rounded. The 

 anterior margin is rather widely reflexed and is useful in aiding the species 

 in their fossorial tendencies. 



The mentum presents important modifications, the simplest being that 

 of leucostictus or saucius, in which the face is quite flat and the margins 

 narrowly reflexed. From this form the mentum becomes more concave 

 and the sides more widely reflexed so that it becomes cupuliform. Those 

 species with the mentum least concave have the posterior margin entire, 

 as the concavity increases we find a slight notch, which in the last four 

 species becomes a rather wide and deep excision semicircular at bottom. 

 These modifications of the mentum form a very natural means of dividing 

 the species. 



The thorax is so modified in form and structure in all the species, that 

 nearly all can be separated by it alone. The simplest form is that of 

 leucostictus which resembles that of Trichius ; apex feebly emarginate, 

 sides feebly subangulate, hind angles rounded, the margin acute posterior- 

 ly, there is no incisure about the front angles nor are there any pubescent 

 spots such as occur in every other species. In planatus the sides are sub- 

 acutely margined, arcuate in front and gradually narrowed behind, not 

 very unlike Iphthimus, in fact the species resembles a Tenebrionide when 

 walking. The anterior angles are small, the notch or fovea within feeble, 

 and there is a notch in the lateral margin which limits the angle. The 

 hind angles are continuous with the margin, not very prominent and limit- 

 ed by an oblique groove within. The next modification in degree is in the 

 Schaumii group, in which the thorax is broader and less depressed, the an- 

 terior angles are feeble, the fovea within them, but no lateral notch in the 

 margin. In two of the species the hind angles are not limited by any 

 groove and the anterior margin of the thorax beneath is not notched. In 

 angular is, however, the hind angles have a limiting groove, and beneath 

 the front angles is a slight incisure. 



The three species following angularis do not present any very important 

 modification of its type, the angles are nearly the same and there is the 

 subangular incisure, but in pilosicollis, we observe a groove running out- 

 ward from the fovea and limiting the anterior angles. This gives the first 

 intimation of the tuberculiform angle which is observed further on. 



In nitens, the front angles begin the nodiform structure by the greater 

 depth of the transverse groove. The hind angles are also much retracted 

 within the line of the sides, and the groove which limits them within is 

 s > deep that the angle is depressed below the surface of the disc of the 

 thorax. 



In passing to variolosus, the anterior angles become so completely sur- 

 rounded by deep grooves as to beoma almost like isolated tubercles, and 

 may be assumed to be the result of the gradual exaggeration of the various 



