138 ZOOLOGY. 



plate, as it has an articulated palpus on each side, much 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 i\\Q jugulum. The labial palpi are attached one on each side of the 

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

 2)araglossce. 



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

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

 surfaces are named respectively tergiim and ]j^cturii. It is composed of 

 three divisions, named prothorax., mesothorax^ and metatJiorax y the upper 

 surfaces of which are termed pronotum., onesonotmn., and metanotum., 

 and the inferior surfaces mitejx'ctus, medi2)€cti(s, and postpectus.^ The 

 protliorax 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 lattei', 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 upper part will he the prcescutmn, scutum, scutellmn, and 2yostsci<r 

 fellum, and those below, the parapte?'a, sternum., episterna, and epimera. 

 The term pleura is aj^plied to the sides in descriptions, but it is not limited 

 ta 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 tegulcG., ov patagia) near the wings. New- 

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

 Diirckheim thinks the part 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, 12-i, 131, 

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

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



The chief appendages 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 acetahida., and 

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

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

 the coxa follows a small articulation named the trochanter / then follows 

 the principal articulation, the femur., or thigh, to which succeeds the tihia., 

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

 calcaria. 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 ^^AaZ^/wi/t^s, of which there are never more 

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

 ^ingues. 



* Frosteffms, d'c, would be more uniform with prothorax, d'c, than antepectus. The name 

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

 of the breast of each thoracic segment. 

 342 



