54 4 AT INTRODUCTION TO ENTOMOLOGY 



adjacent parts. The condition found in a cockroach may be taken 

 as typical. In this insect the trcchdntin (Fig. 65, t) is a triangular 

 sclerite, the apex of which points towards the middle line of the body, 

 and is near the ventral articulation of the coxa (Fig. 65, y). In most 

 specialized insects the trochantin is consolidated with the antecoxal 

 piece, and the combined sclerites, which appear as one, are termed 

 the trochantin. 



The antecoxal piece. ^ Between the trochantin and the episternum 

 there are, in the cockroach studied, two sclerites; the one next the 

 trochantin is the antecoxal piece. This is the articular sclerite that 

 articulates directly with the coxa (Fig. 65, ac). As stated above, the 

 antecoxal piece is usually consolidated with the trochantin, and the 

 term trochantin is applied to the combined sclerites. Using the term 

 trochantin in this sense, the statement commonly made that the 

 ventral articulation of the coxa is with the trochantin is true. 



The second antecoxal piece. The sclerite situated between the 

 antecoxal piece and the episternum is the second antecoxal piece (Fig. 

 65, 2 d ac). This is quite distinct in certain generalized insects; but it 

 is usually lacking as a distinct sclerite. 



The articular sclerites of the wings. In the Ephemerida and Odo- 

 nata the chitinous wing-base is directly continuous with the walls of 

 the thorax. In all other orders there are at the base of each wing 

 several sclerites which enter into the composition of the joint by which 

 the w r ing is articulated to the thorax ; these may be termed collectively 

 the articular sclerites of ike w'ngs. Beginning with the front edge 

 of this joint and passing backward these sclerites are as follows: 



The tegula. In several orders of insects there is at the base of the 

 costal vein a small, hairy, slightly chitinized pad; this is the tegula 

 (Fig. 66 , Tg) . In the more highly specialized orders, the Lepidoptera, 

 the Hymenoptera, and the Diptera, the tegula is largely developed 

 so as to form a scale-like plate overlapping the base of the wing. 



The tegula3 of the front wings of Lepidoptera are specially large 

 and are carried by special tegular plates of the notum. These, in turn, 

 are supported by special internal tegular arms from the bases of the 

 pleural wing-processes (Snodgrass, '09) 



The axillaries. Excepting the tegula, which is at the front edg3 

 of the wing-joint, the articular sclerites of the wings have been termed 

 collectively the axillaries. Much has been written about these 

 sclerites, and many names have been applied to them. The simplest 

 terminology is that of Snodgrass ('09 and '10 a) which I here adopt. 



