10 



RHYNCHOPHORA OF NORTH EASTERN AMERICA. 



Fig. 5. Head of 

 sonus, showing the 

 widened at apex. (Orig- 

 inal.) 



Cos- 

 beak .,4- 



A further modification of the beak by which it becomes bent 



beneath the head and more or less received, 

 in repose, within a groove in the breast, is 

 found in the tribes Cryptorhynchini, Oeu- 

 torhynchini and Zygopini, and in the sub- 

 family Thecesternina 1 . This form of the 

 IK ak is shown in the figure of Craponlns 

 in <cqnal is Say, under the tribe Ceutorhyn- 

 chini. The beak is often slightly enlarged 

 apex and in the genus Cossoniis 

 (Fig. .1), it is very much widened or 

 dilated. At the sides of the beak there are frequently seen 

 more or less definite grooves or scrobes for the reception of 

 the antennae; the position on the beak varies, and the direction 

 may be directly towards the eye or more or less below it. as shown 

 in Fig. 6. 



The deciduous cusps of the mandibles,, which characterize the 

 subfamily Otiorhynchinse, are seldom to be seen, 

 on account of their being lost soon after the 

 adult emerges from the pupa, but the scar mark- 

 ing the point of attachment is permanent. 

 Figure 7 shows the tip of the beak of a speci- 

 men in the junior author's collection in which 

 the cusp itself has been preserved on one mandi 

 ble, while the scar shows on the other. fig. 6. A, 



nal groove lateral and 



The mandibles are alwavs small and situated directed towards the 



eye; B, arrlennal 



often within the end of the beak, but there are groove directed be- 

 neath the eye. (After 



two variations readily observed and useful in Biei.) 

 classification. In Rlii/nc-lt'itcx they are toothed on the outer side, 

 so that the teeth show plainly as two little triangular projections 



even when, as is usually the case, the man- 

 dibles are folded. They become conspicu- 

 ous, as shown in Fig. 8, when the mandi- 

 bles are open. 



The motion of the mandibles is usually 

 horizontal, the teeth consequently being- 

 visible from above, as shown in Figs. 8, 

 10 and 11, but in Balaitinus the reverse is 

 the case and the motion is vertical, so 

 of that the teeth of the mandibles show from 



Fig. 7. Tip of beak 

 Otioi /.' Yiu-hus sulcatiis,\ A 

 cusp in place; B, mandibular 

 (Original.) 



the side view only. (Fig. 



