COLEOPTERA. 35 



considered them as mere tubercles. Curtis and Brulle have, however, 

 recently discovered a small frontal tubercle in some of the Dermes- 

 tidae, which appears to be an ocellus, as it is indeed named by the 

 former. The mouth consists of an upper lip, generally transverse ; 

 a pair of horny jaws ; a pair of lower jaws of less firm consistence, 

 furnished with an articulated palpus, and a lower lip, also furnished 

 with a pair of similar but shorter palpi ; the lip itself (labium) 

 arises from a transverse horny plate (mentum), articulated at its 

 base with the head. The second segment is by far the largest ; 

 it is generally termed the thorax, but, strictly, it is only the first 

 thoracic segment (prothorax), having the fore-legs articulated to it 

 on the under side. Latreille has claimed the discovery of a pair 

 of spiracles on the inner membrane of this segment ; Messrs. Kirby 

 and Spence had, however, previously noticed it. {Lntrod. iii. p. 4S.) 

 The second thoracic segment (mesothorax) is very short, and is 

 scarcely visible from above when the insect is at rest, the only ex- 

 posed part consisting of a triangular plate (scutellum, or, more 

 strictly, scutellum of the mesothorax), on each side of which the 

 elytra are attached ; this segment also bears on its under surface the 

 middle legs. The third thoracic segment (mesothorax) is larger in 

 size than the preceding, bearing on its upper surface, near the anterior 

 angles, a pair of membranous wings, and on its under surface the pos- 

 terior legs, of which the basal joint is large and transverse. The ab- 

 domen is intimately attached by its entfre breadth to this last tho- 

 racic segment, and generally consists of six or seven segments (the 

 typical number being nine), each having a pair of spiracles at the 

 sides, or upper surface ; the tarsi vary in the number of the joints, 

 from two to five. 



In an order of such extent as the present, it is not surprising that 

 some few variations from these typical characters should exist ; thus 

 in some, as the females of the Glowworm and Drilus, the organs 

 of flight are entirely wanting. Many genera of Carabida?, Curculionida;, 

 &c. have elytra, but no wings : in some the elytra are soldered 

 together ; others again, as Molorchus, Buprestis, &c. have the wings 

 only longitudinally folded ; others, as Meloe, have the elytra lapping 

 over each other ; and in some the elytra are narrowed, and do not 

 meet in a straight line down the back, — Sitaris, <S:c. The only 

 character which prevails throughout the order is that derived from 

 the metamorphosis, which is of that species which has been termed 



D 2 



