138 ZOOLOGY. 



plate, as it has an articulated palpus on each side, mucli like those of the 

 former organs. The labium is partly covered by and articulated with the 

 mentum^ which is articulated to the anterior part of the cranium^ beneath 

 named the Jugitltim. The labial palpi are attached one on each side of the 

 labium near the tongue. The projecting sides of the tongue are named 

 pai-cujlossiü. 



Thorax. The thorax supports the organs of motion, and is attached to the 

 head of an insect by a membranous connexion. Its entire upper and lower 

 surfaces are named respectively tergmn and lyectum. It is composed of 

 three divisions, named j^f^othorax^ mesothorax.^ and metatJwrax / the upper 

 surfaces of which are termed iwonotum.^ mesonotum., and metanotiLm., 

 and the inferior surfaces antejyedus^ Tnedljyectus^ and jpostjpectus:''' The 

 prothorax bears the anterior pair of feet, but as it bears no wings it is 

 simpler in its structure, and its theoretical parts are more difficult to discover 

 than those of the two other thoracic segments. It is in the latter, therefore, 

 that we must look for the subdivisions of these segments. These are 

 generally enumerated from the front backwards, when the four subdivisions 

 of the uj5per part will be the prcßSGutum.^ scutum.^ scutellum.^ and posUcxju- 

 Ullum., and those below, 'C^\% jparajptera.1 sternum., episterna., and epimera. 

 The term pleura is applied to the sides in descriptions, but it is not limited 

 to any particular part. The sternum is the chief central part with which 

 the two episterna articulate, and the two epimera are near the insertion of 

 the feet, and the paraptera (or tegulce., or patagia) near the wings. New- 

 port tliinks it exists in a rudimentary condition in the prothorax, but Straus 

 Dürckheim thinks the ])art referred to by that author is the rudiment of 

 another segment. The mesothoracic scutellum is often seen wedged 

 between the base of the elytra in the Coleoptera {pi. 81, figs. 23, 124, 131, 

 &c.) The prothorax and mesothorax have usually each a pair of spiracles, 

 but in the Hymenoptcra the second pair is upon the metathorax. 



The chief ajipendages of the thorax are the feet, which are never absent. 

 These organs have many modifications to adapt them to their various uses 

 of walking, swimming, grasping, leaping, digging, &c. The thoracic 

 cavities into which the base of the feet is fitted are named aoetabula.^ and 

 the basal part of the limb which enters them is the coxa ^ but this is 

 sometimes firmly attached, so as to have no independent motion. ISText to 

 the coxa follows a small articulation named the trochanteT ', then follows 

 the principal articulation, \\\e ferrvm\ or thigh, to which succeeds the tibia., 

 which is often armed at the end with fixed or movable spines, named 

 dalcaria. This part is more generally provided with spines and cilia than 

 the other parts. The tibia is followed by the tarsus, which is made up of 

 several small articulations named j!?ÄaZ<:m^<?s, of which there are never more 

 than five. The end of the tarsi is usually armed with two claws named 

 ungues. 



* ProstethuR, d'c, woukl be more uniform with prothorax, dw, than antepectus. The name 

 prosternum cannot be used witli propriety, as it is applied to a minor division (sternum, episterna) 

 of the breast of each thoracic segment. 

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