CRUSTACEA, ARACHNIDES, INSECTA. H9 



Distance, in the orifices of the tracheae, and Marcel de Serres,&c. 

 in the palpi ; neither of these opinions, however, are corroborated by 

 positive and conclusive facts. A> t< the second, it is only in the 

 Crustacea Decapoda, and some few of the Orthoptera, that we can 

 find a visible ear. 



The mouth of these animals presents a great analogy, which, 

 according to Savigny*, and at least with respect to the Hexapoda, 

 extends to those which can only feed by the suction of liquid 

 aliment. 



Those called Tritores or Grinders (broyeurs), on account of their 

 having jaws fitted for triturating their food, always present them in 

 lateral pairs, placed one before the other; the anterior pair are 

 .-ially called mandibles ; the pieces which cover them before and 

 In-hind are named labia^, and the front one, in particular, labrum. 

 The palpi are articulated filaments attached to the jaws or to the 

 lower lip, 'and appear to be employed by the animal in recognizing 

 its food. The form of these various organs determines the nature 

 of the regimen with as much precision as the teeth of quadrupeds. 

 The //r/u/a, or tongue, commonly adheres to the lower lip J. Some- 

 times, in the Apes and other Hymenopterous insects, it is consider- 



organ, Bullet. <les Sc. Nat. ; but he adduces no one direct experiment in proof of his 

 opinion. It would, if this were so, seem probable that in the highly carnivo- 

 rous Crustacea, such as the Gecarcini and others, we should find this organ in a com- 

 paratively greater state of development, whereas the fact is directly the reverse. His 

 ideas respecting the external composition of the Crustacea Decapoda suppose the 

 existence of a skeleton. He should have commenced, however, by establishing the 

 connexion of these animals with the Fishes, and not by admitting, as a positive fact, 

 what is at least a matter of doubt. 



* Memoirc sur les animaux sans vtrtebres. The original idea was thrown out, but 

 undeveloped, in ray Hist. Gen.des Inscctcs. 



t We here more particularly alude to insects with six feet, or to the Hexapoda. 



J Or rather labiuin, since the other is termed labrvm. It is protected, before, by 

 a horny production formed by a cutaneous prolongation, and articulated at the base 

 .m inferior portion of the head called the mcntum or chin. Its palpi, always two 

 in number, nrc distinguished from those of the maxillae by the epithet labial. When 

 tter amount to four they are designated as external and internal ; they are con- 

 sidered as a modification of the external and terminal division of the maxillae. This 

 production, \\hieh, In his Ulonates or the Orthoptera, Fabricius termed the Galta, is 

 still the same maxillary division, but more dilated, arched, and fitted to cover the 

 internal division which, here, on account of its scnly consistence and of its teeth, 

 resembles a mandible. In the last insects, and particularly in the Libellulae, the 

 interior of the huccal cavity presents a soft or vesicular body, distinct from the lip, 

 and which, compared to the Crustacea, appears to be the true tongue labivm, Fab. 

 This part is perhaps represented by those lateral divisions of the ligula termed para- 

 gloss*. (9ee the Coleoptcra Camivora, Hydrophili, Staphylini, the two pencil- 

 shaped pieces that terminate the lip of the Lucani Apiariw, &c.) The above- 

 mentioned Insects, the Orthoptera and the Libcllulne of Linnreus, evidently demon- 

 strate that this membranous and terminal portion of the inferior lip, which projects 

 more or less bet , i, j-.r.d i< particularly elongated in several of the Hyme- 



noptcra, is very distinct from that internal caruncle which I consider the tongue 



