DYNASTIN.E 239 



moderate in point of size. The head is of the usual very moderate 

 size and coarse rugose sculpture, the clypeus finely pointed to broad 

 and sinuato-truncate at tip, and the frontal ridge is obsolete or 

 represented by two small and feeble tubercles. The mandibles 

 are well developed and variably tridentate, frequently less strongly 

 so in the female; the antennae are of the usual lo-jointed type, with 

 the 3-jointed club regular and not as in Pentodon. The pronotal 

 cavity of the male is very large and deep, and the lateral extremities 

 of its posterior margin are elevated into conspicuous corniform 

 processes, which, in the less developed males, become nearly as in 

 the female, where the cavity differs from that of Anastrategus in 

 having its posterior margin abrupt and transversely crescentic, not 

 continuous in any way with the lateral and anterior margins of the 

 depression; the apical tubercle of all the preceding genera is here 

 greatly extended upward in the fully developed males, especially 

 those of the antceus group, forming a long curved horn, and the 

 cavity is frequently devoid of all sculpture in the fully developed 

 males, but in successively more depauperate individuals there is an 

 increased invasion of the rugose sculpture so fully developed in the 

 females. The pygidium is never much larger in the male than in 

 the female, where the transverse convexity is often more developed, 

 the entire plate being as in Anastrategus; the legs and slender hind 

 tarsi, with undilated basal joint, are also as in that genus, and the 

 post-coxal process of the prosternum is densely herissate with erect 

 setse as in Ligyrus. Our species are assignable to two groups, 

 which, as in the case of Anastrategus, are essentially geographic, 

 but in this case subgenerically different, as follows: 



Body larger in size, more elongate and more convex, the cephalic tubercles 

 evident; mandibular teeth very unequal and broadly rounded; 

 two posterior horns of the prothorax generally shorter and broader, 

 though sometimes as in the next group; external sinus of the posterior 

 tibiae with a single shorter tooth at the bottom and with two long 

 setae; sutural stria always deep and distinct Group I 



Body smaller, much more abbreviated and less convex, the cephalic 

 tubercles obsolete, the mandibular teeth high and prominent, less 

 unequal among themselves in the female as a rule, the posterior 

 pronotal horns more slender, the sutural stria of the elytra frequently 

 obsolete, the external sinus of the hind tibiae crenulate at the bottom 

 and with more numerous and shorter setae Group II 



The first of these groups is represented by many species and sub- 

 species from Louisiana to southern Brazil, while the second is confined 



