of the Amazon Valley. 47 



Fam. LONGICORNES, Latr. 



Tribe L ami aires, Latr. 



Subtribe Acanthoderit^, Thorns, (pt.). 



Group Acanthoderinee. 



Genus Acrocinus, lUiger. 



(Thorns. Class, des Cerambyc. p. 28.) 



This genus, as revised by Thomson, is distinguished from 

 Oreodera and all the allied genera by the simple femora. To 

 this may be added that in Oreodera the basal joint of the an- 

 tenna is almost always relatively shorter and more abruptly 

 clubbed than in Acrocinus; and the S fore tarsi are naked in 

 the latter, whilst they are always fringed with hairs in the former 

 genus. The anterior acetabular sutures are widely gaping. 

 The face in all the species is short, being nearly twice as broad 

 as long (measuring the length from the top of the antenniferous 

 tubercles) ; the muzzle is widened from the eyes downwards, 

 and the lower angles are prominent. The eyes above nearly 

 meet on the vertex, being separated only by the central line ; 

 below they reach the central line of the forehead only in one 

 species {A. lungimanus) , in the others being widely separated. The 

 fore and middle tibial grooves, with their accompanying tubercles, 

 are removed to very near the apex of the tibiae in A. lungimanus ; 

 in A. trochlearis and ^. accentifer they are largely developed, 

 especially in the 6 . The fore legs are covered with granula- 

 tions and elongated in the 6 of the two species just named, 

 and the tibiae have a row of tooth-shaped projections along their 

 under- surface. In A. longimanus the same legs are tubercu- 

 lated in both sexes, the denticulations of the tibi?e are very 

 large (extremely so and recurved in the $ ), whilst the fore legs 

 of the 6 reach an excessive length, the femora having also a 

 strong tooth-shaped projection on the upper surface near the 

 base, which does not exist in the 6 of the other species. The 

 thoracic lateral spines are long, acute, and retrocurved in A. 

 longimanus ; in the other species they exist only as points at the 

 apices of the lateral tubercles. There are several other points of 

 difference between O. longimanus and its congeners; but I think 

 they are not of a nature to warrant the institution of a separate 

 genus ; the species must be viewed rather as a highly developed 

 and exaggerated form of the generic type. 



An erroneous statement has been made and repeated by 

 authors with regard to the thoracic tubercles of A. longimanus, 

 to the effect that they are moveable. Such a structui'c would 

 be curious in the highest degree, but it does not seem to have 

 excited attention sufficient to lead to further examination. It 



