of the Amazons Valley. 215 



the ridge formed by the shoulders, and disappears before reach- 

 ing the apex. The elongated basal joint of the antennse has the 

 same outline as in the great body of the Acanthocinitse previously 

 described. The anterior coxae are somewhat globular, and the 

 acetabular suture is quite closed ; both pro- and meso-sterna are 

 plane, the former being very narrow and the latter subquadrate, 

 narrowed behind. The apical segment of the abdomen is not 

 prolonged into an ovipositor in the female ; it varies so much in 

 form in the two sexes, especially as to the outline of the apices 

 of the ventral and dorsal plates, that it affords no constant cha- 

 racters for the formation of groups within the genus. The males 

 are larger and more robust than the females, the anterior legs 

 also being longer and stouter, and having dilated and fringed 

 tarsi. In these typical forms the body is somewhat depressed 

 above, with a very gradual and slight slope posteriorly ; with this 

 the elytra are narrowed nearly in a uniform degree from base to 

 apex, and the thorax is widest at its hind angles, with a gradual 

 attenuation from its base to its apex. 



These characters, however, do not hold together so as to form 

 a well-defined genus. Some species, which in all other respects 

 are true Colobothea, recede from the typical forms in the shape 

 of the thorax. Thus C. Schmidtii has a thorax approximating 

 to that of some members of the Leiopodine group, having a 

 lateral tubercle towards the hind angles ; and C. lineola presents 

 a thorax of nearly the same form as (Edopeza, Trypanidius, and 

 the allied genera. The dilatation of the male tarsi also fades 

 away from species to species, and some of these aberrant forms 

 have the elytra less depressed and more narrowed near their 

 apices than in the more typical Colobothea. Notwithstanding 

 this diversity, I have failed in my attempts to divide the genus. 

 One of the aberrant forms constitutes the genus Priscilla of 

 Thomson (Systema Oeramb. p. 30). It is much less elongate 

 and more convex than the true Colobothece, and the shoulders of 

 the elytra form a larger and more elevated ridge; I have not 

 ventured, however, to separate it from the rest whilst many 

 other species equally entitled to form distinct genera remain in 

 the genus. 



§ I. Fore tarsi not more dilated in the male than in the female. Thorax 

 narrowed at the base, and tumid or tuberculated behind the middle on 

 each side. 



1. Colobothea lignicolor. 



O. modice elongata, brmmea cinereo nigroque vaiiegata, corticis 

 fragmentum simulans ; elytris apices versus subito attenuatis, 

 apicibus minus late sinuato-truncatis utrinque bispinosis, dorso 

 costatis. Long. 6 lin. $ . 

 Head clothed with tawny-brown pile. Antennse twice the 



