of Rhynchophorous Coleoptera. 



293 



In Rhynchophora the prothoracic sutures are obliterated ; 

 there is no separation between the prosternum and episterna, 

 and very rarely between the latter and the pronotum ; the coxal 

 cavities^ frequently confluent, are always closed behind, by the 

 epimera, which become connate on the median line, enclosing 

 the hind part of the prosternum, thus cutting it off completely 

 from the mesothoracic segment. 



Fig. 5 represents this arrangement of parts in a Brenthide, 

 in which family the extreme limit of degradation by linear ex- 

 tension is reached. Fig. 6, under surface of prothorax of a 

 Calandride [Tthynchophorus) . Fig. 7, ditto of Crypt 07-hynchus. 

 Fig. 8, ditto of Balaninus. Fig. 9, ditto, Ophryastes. Fig. 10, 

 ditto, Thecesternus. Fig. 11, ditto, Dend?'octonus. 



When the coxse are contiguous, the point of the prosternum 

 is visible behind them, but is none the less perfectly enclosed 

 by the growth of the side pieces to the median line. 



Another evidence of the inferiority of type of the Rhyncho- 

 phora, which has not been mentioned, is seen in the functions 

 performed by the beak, which in the lower groups, especially in 

 the female, becomes greatly elongated. The occurrence of cor- 

 neous exserted ovipositors in other orders of insects is not rare ; 

 a few species of Coleoptera (certain Valgus, for example) have 

 the last abdominal segment prolonged, simulating such an organ; 

 but it was reserved for the Rhynchophora to exhibit a degrada- 

 tion of type by which a function, peculiarly appropriate to the 

 posterior extremity of the body, is performed by the head — the 

 elongated beak becoming, in fact, the ovipositor. 



Thus the inferiority of grade, evidenced in other series of 

 Coleoptera by the softness of the integuments or by the perma- 

 nence of larval forms, chiefly in the abdomen and coxa3, is in 



