430 Annals Entomological Society of America [Vol. VI, 



Thorax 



Prothorax. — The prothorax is a large chitinous segment whose 

 sclerites are solidly fused together, with the exception of the 

 episternum and epimeron which are separated for a short dis- 

 tance by the coxal cleft (b) . 



The notum (no) overlaps the prescutum, scutum, and a por- 

 tion of the scutellum of the mesothorax dorsally ; and the pleural 

 region projects over a portion of the anterior part of the meso- 

 thorax laterally (PI. LV, f. 1 and 4). The tergum or notum is 

 of one piece, its sclerites being indistinguishably fused together. 

 Its anterior portion is more or less irregular due to the attach- 

 ments of the muscles of the fore leg to its inner surface. The 

 union of the notum and pleuron forms a well defined ridge. 



The Pleuron (pi) is divided, as stated above, by the coxal 

 cleft into the epimeron (epm) and episternum (eps). The cleft 

 extends only a short distance into the pleuron terminating in a 

 groove. Above this the pleuron bulges out forming a larger 

 cavity for the expanding muscles of the fore leg. This region of 

 the pleuron is called the omium (om). 



The sternum (st) is a small area lying between, and anterior 

 to the coxal cavities, and is indistinguishably fused with the 

 pleuron. The portion of the sternum projecting backward 

 between the coxal cavities is called the mucro (mu) . The anter- 

 ior portions of the coxal cavities are formed by the inner surfaces 

 of the epimeron, episternum, and the sternum; and are closed 

 posteriorly by the extensions of the prothorax epimeron and 

 sternum, together with the anterior portion of the mesosternum. 



The legs show the usual five divisions into the coxa (co), 

 trochanter or fulcrum (fr), femur (fe), tibia (t), and tarsus (ta), 

 (PI. LVI, f. 13). Since the fore legs are typical, although they 

 are proportionately smaller, one description will be sufficient. 

 At the base of the coxa hidden within the coxal cavity is a nar- 

 row plate called the trochantin (PL II, f. 9 ti). The coxa is 

 a large swollen segment lying largely within the coxal cavity 

 and is freely movable. The trochanter or fulcrum is a small 

 segment which forms a ginglymus articulation with the coxa 

 and is obliquely joined to the side of the femur. The femur is 

 long and more or less spindle shaped; the tibia articulates with 

 it by a ginglymus joint and is long and slender. The tarsus 

 is composed of three segments. The first segment is called 



