178 Prof. J. C. Schiodte on the Classification 



spiracles. With the exception of the middle line^ this large 

 head will be found filled by the powerful flexors of the mandi- 

 bleSj reaching to the foramen occipitale, which is very large and 

 entirely transferred to the under surface of the head. The head, 

 then, is for the greater part hidden in the prothorax as in a 

 sheath, fixed all around and directed by the powerful muscles 

 of the neck. The whole of the part which is placed inside the 

 prothorax is only sparingly chitinized; but the action of the 

 muscles of the neck extending between the outside of the skull 

 and the walls of the prothorax makes up for any loss of support 

 which could arise to the mandibular muscles from the want of 

 hardness in the skull. During the act of burrowing, the pro- 

 thorax is firmly ensconced between the walls of the gallery, the 

 numerous grains of chitine with which its surface above and 

 below is generally beset increasing the firmness of its posi- 

 tion ; and thus every requisite condition is provided — a firmly 

 placed prothonix affording support for the muscles of the neck 

 in guiding the head forwards and backwards and to the sides, 

 and the skull inserted as in a sheath giving support to the 

 enormous mandibular muscles. 



The immense size of the head and its deep insertion into the 

 prothorax, of course, are the causes of the peculiar shape and 

 unusual size of the latter part, which has further contributed to 

 confound the views of entomologists on the structure of the 

 larvae of Buprestidse*. It has been overlooked by all that in 

 this case one part of the prothorax is developed at the cost of 

 the others — namely its anterior portion, the so-called collar (col- 

 lare pi'othoracis), which is found in all larvae and all imagos of 

 insects with more or less inserted neck, but which in the larvae 

 now before us is immensely increased in size. In my paper 

 on the larvae of Coleoptera, published in the ' Naturhistorisk 

 Tidsskrift,^ I describe the dorsal part of this collar as praetergum 

 pronoti. The rest of the prothorax, which is elsewhere much 

 the larger, and which serves the locomotory system by accom- 

 modating the fore legs, is in this case to such a degree reduced 

 that it seems to be entirely wanting, and the large spiracula 

 thoracica have not been able to find room as usual on the pro- 

 thorax, but have been transferred to the lateral folds of the next 

 ring, pleurae mesothoracis. The larvae of Trachys being de- 

 scribed as possessing a free head and short legs, it will, no 

 doubt, be found that the larvae of Buprestidae will show the same 



* In the Mem. de I'Acad. des Sc. de Lyon, 1851, pp. 116-120, M. Ferris 

 has given a minute summary of the discussion between Goureau, Lucas, 

 and Leon Dufour on this subject. Although each of the four authors now 

 and then has got hold of the clue for a moment, they have always lost it 

 again, and none of them has succeeded in solving the problem. 



