26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO7 



and clypeus by an epistomal sulcus (C, D, G, I, es), in others it is 

 not SO divided (A, B, E). 



The larvae of Buprestidae present on the inner surface of the 

 dorsal wall of the cranium a system of strong, branching ridges (fig. 

 8F). The vertex is deeply emarginate for the insertion of long 

 muscles from the thorax, but from the apex of the cleft a thick, 

 median, internal ridge (FR) runs forward to the strongly sclerotized 

 clypeal plate (Clp) and gives off a pair of diagonal side branches to 

 the lateral parts of the clypeus. From the proximal end of the median 

 ridge two lateral ridges turn back to the occipital margin of the 

 cranium and are continuous around the latter with the thickened edges 

 of the cleft of the vertex. In a surface view of the head the grooves 

 of inflection that form these cranial ridges are visible as fine lines 

 through the middle of the ridges. On the larval head only the frontal 

 arms of the cleavage line are present ; they are pale, weak, double- 

 edged linear tracts of the cuticle (CL) diverging from the apex of 

 the notch in the vertex to the bases of the antennae. Between the 

 upper ends of the arms arise the muscles of the labrum. 



The structural contrast between grooves of cranial ridges and the 

 lines of cuticular cleavage is so pronounced that there can be no mis- 

 taking one for the other. Yet, Cook (1943) would identify the arms 

 of the frontal ridge in the buprestid larva with the cleavage lines of 

 the Corydalus larva (fig, 10 A), for no other reason, apparently, than 

 that in each case the lines go mesad of the antennae. The cleavage 

 lines of the buprestid larva Cook terms "postf rental sutures," and the 

 V-line formed by the branches of the median frontal ridge he calls 

 the "clypeofrontal suture." To say the least, such an interpretation 

 results in a most confusing inconsistency and is in no way necessary. 

 The fact appears to be simply that the frontal area between the 

 cleavage lines of the buprestid larval head is reinforced by ridges to 

 brace the otherwise weakly sclerotized cranium against the strong 

 clypeal plate, which carries the mandibles ; the cranium is thus enabled 

 to withstand the pull of the huge mandibular muscles, the bases of 

 which cover almost the entire parietal regions. If the frontal ridges 

 were absent, there would be little to distinguish the head of a bupres- 

 tid larvya from the head of any other beetle larva. A median ridge 

 extending from the occipital margin of the head to the clypeus is 

 present also in larvae of Chrysomelidae (fig. 8 G, mcs), but in the 

 adult (H) all the larval lines except the epistomal sulcus are absent. 



The lines of cuticular cleavage in the larva are probably not 

 retained in any adult beetle, though other lines of the adult head have 

 frequently been mistaken for them, which is to say, they have been 



