xii INTKODUCTIOX. 



the corneous plate formed b}' the coalescence of the posterior lateral 

 elements (epimera) is very narrow ; and in other cases (Baris, &c. ) the 

 posterior part of the prosternum is thickened and overlies the suture on the 

 median line, but without coming into contact with the mesosternum. 



4th. The ventral segments never exceed five in number, and the first 

 and second are usually larger and more closely connected, frequently even 

 connate, with partially obliterated suture ; the fifth is sometimes longer 

 than the fourth, sometimes about equal to it. 



5tli. AVhen there is any appreciable difl'erence between the sexes, it is 

 usually manifested by a greater elongation of the beak of the $ 9 > indi- 

 cating its use as an accessory organ of generation, for making the perfora- 

 tion in which the egg is subsequently placed by the soft ovipositor, and 

 pushed down by the beak. 



Gth. The other sexual diflference is in the addition of a small dorsal (or 

 anal) segment to the (j^cf ; this character is, however, not obvious in 

 several families, the morphological representative of this anal segment 

 being completely retracted and covered by the pygidium. In others this 

 segment is visible only from beneath, simulating, therefore, a sixth ven- 

 tral. 



7th. The very rare occurrence of articulated movable spurs at the end 

 of the tibial; it is seldom, indeed, that more than one fixed mucro occui's, 

 and in the species in which the tarsi are inserted laterally near the tip, this 

 mucro becomes frequently elongated and curved ; the outer angle of the 

 tip is in these instances quite ofcen prolonged into a curved digitation, like 

 the terminal tooth of the front tibia3 of some Scaritini, of the family 

 Carabkla. 



8th. The head is most frequently prolonged in front of the eyes, forming 

 a beak, wliich is usually narrower than the front, and frequently very 

 slender. A flattened prolongation, similar to a beak, occurs in some genera 

 of Cucujiclw, Pythldm and (EdemeridcB, but not elsewhere in the normal 

 Coleoptera. 



9th. In the vast majority of species the labrum is wanting; in some 

 Scolytid<e it is feebly developed, but is present in normal form only in 

 Rhinomaceridm and Anthribidm. 



10th. Except in Bhino mace r idee and Anthribidce the palpi are short and 

 rigid, with the joints diminishing in size; in those families they are slender 

 and flexible, as in normal Coleoptera. 



11th. In those genera in which the hind tibiae are truncate and margined 

 at tip, forming a surface called a corbel, this surface may be glabrous or 

 scaly. In normal Coleoptera they are always glabrous, and in Hypoceph- 

 alus alone they are densely clothed with hair.* 



12th. A peculiar ridge on the inner surftice of the elytra, into which the 

 ascending margin of the metathoracic epimera and ventral segments fit, 

 giving great firmness and solidity to the hinder part of the body. This 



* LeContc, Trans. Am. Ent. Soe. v, 209. 



