222 HETEROMERA. 
has these organs very distinctly clavate. A. dituberculatus has a stout conical tubercle 
on either side of the suture at the base. Good specific characters are sometimes to be 
found in the form of the fifth ventral segment of the males: this segment in the 
majority of our species is unimpressed, but in some of them it is foveate or transversely 
concave in the middle ; the apex is usually truncate, sometimes emarginate. 
The American synonymy only is quoted. 
The following table will assist in the identification of the Central-American 
species :— 
Thorax strongly constricted behind the middle, the sides not denticulate *, 
the flanks more or less deeply grooved or excavate above the ante- 
rior cox. 
Elytra with a deep or distinct post-basal depression and tuberculate or 
transversely swollen at the base, rounded at the apex (the sides 
more obliquely converging behind in A, dromedarius &c.). 
Anterior portion of the thorax gibbous; the disc transversely 
grooved behind the middle; antenne feebly clavate. 
Elytra moderately tuberculate at the base. . . . . . . Species 1. 
Elytra sharply tuberculate at the base. . . . . . . . Species 2. 
Anterior portion of the thorax gibbous; the disc not transversely 
grooved behind the middle; antennz strongly clavate . . Species 3. 
Anterior portion of the thorax transversely convex ; the posterior 
portion more or less cylindrical, sometimes dilated laterally 
at the base; the disc not transversely grooved behind the 
middle (viewed laterally and longitudinally, sloping or 
gradually rounded to the base). 
Apical joint of the maxillary palpi moderately broad ; elytra 
spotted or fasciate. 
Antenne slender . . . . . . . . 1... . Species 4-9. 
Antenne very stout . . - . . . Species 10, 11. 
Apical joint of the maxillary palpi very iy breed’ * elytra uni- 
colorous, sometimes paler at the base. 
Head short, rounded at the sides behind. . . . . . Species 12-16. 
Head longer, more obliquely narrowed behind. . . . Species 17. 
Anterior portion of the thorax transversely convex ; the posterior 
portion gibbous ; apical joint of the mee ee very 
broad. . . . . Species 18, 19. 
Elytra a little flattened on the ‘disc, ronnded ’ at the apex, silone 
thorax obsoletely bituberculate in the middle at the base . . Species 20. 
Elytra with a shallow post-basal depression or merely a little flattened 
below the base, the sides more obliquely converging behind. 
Surface coarsely punctured at the base . . . 2... 2. Species 21. 
Surface almost smooth . . . . . . . 1... 1. Species 22, 23. 
* In some specimens of A. clavicornis one or two indistinct teeth are visible. 
