412 EXTERNAL ANATOMY OF INSECTS. 



tribe ; and in the Capricoms you would find that the ge- 

 neral conformation in this respect belonged to our learned 

 author's second mode of solid articulation, resembling 

 that of the majority of the weevils {Curculio L.), in which 

 the head has no projecting angles or tubercles, or other 

 elevation, but is received usually into the circular cavity 

 of the prothorax. 



His third mode of this articulation, that of the Hijmeno- 

 ptera and Diptera, is so peculiar, that it ought to be con- 

 sidered as a primary kind ; since in this the head moves 

 upon the prothorax as upon a pivot, and has a kind of 

 versatile motion. 



With regard to his fourth mode, which from his de- 

 scription appears to be that of Apoderus Oliv., he allows 

 motion to the head only in one direction, observing that 

 the lower margin of the prothoracic cavity has a notch. 

 But M. Latreille calls the articulation of the head in this 

 genus an Enarthrosis a , which admits motion in every di- 

 rection ; and if you examine the common species (A. Co- 

 ryli), you will find that the prothorax has a sinus taken 

 out of its upper margin, as well as out of its lower one — 

 which at any rate will allow a motion upwards. 



I merely mention these little inaccuracies, with due 

 diffidence, as some apology for giving you a different and 

 at least a more popular and general view of this part of 

 my subject, which I shall now proceed to state to you. 

 It seems to me most convenient for the Entomologist, and 

 most consonant to nature, to divide insects, with respect 

 to the articulation of the head with the trunk, into three 

 primary sections, each admitting one or more subdivi- 

 sions. 



a Gen. des Crustac. el Ins, ii. 246. Regne Anim. iii. 325. 



