Fig. lo. Diagram of a thoracic 

 segment (after Comstock). 



a, praescutum ; i, scutum ; c, 

 scutellum ; d, post scutellum ; e, 

 episternum ; /", epimeron ; £-, par- 

 apteron ; /, sternum ; a, 6, rand d, 

 taken together form the tergum ; 



1890.] ENTOMOLOGICAL NEWS. I4I 



writers refer to this sclerite as fhe scutellum. Of the four sclerites 

 which compose the tergal portion of 

 each thoracic segment, the scutum is 

 usually the largest; the scutellum is the 

 second in importance ; while the prae- 

 scutum and the post-scutellum are fre- 

 quendy but little developed' ' (Comstock) 

 The sternum consists of but one 

 sclerite. 



The sclerites of the pleurum are the 

 epistermim and the epimeron, and some- 

 times a third, the parapteron. Their 

 position is shown in fig. lo. The par- 



.?, /and ^, taken together form aptcrou in different groups of insects 



the pleurum. 1 , i n 1 1 7 z 7 



has also been called the tegtila, scaptila 

 and patagmm. The thoracic spiracles^ pierce a small piece of 

 the pleurum called the peritreme. 



Attached to the thorax are the organs of locomotion — the legs 

 and the wings. 



The leg, or the foot of an insect, as it is indifferently called, 

 consists of five parts, the coxa, trochanter, femur, tibia and tarsus. 

 The coxa, or hip joint, is the basal part, and is attached to its 

 thoracic segment near the lateral border of 

 the sternum, sometimes so firmly as to be im- 

 movable. A small sclerite is sometimes found 

 between the coxa and the epimeron, called 

 the irochantin. The trochanter is between 

 the coxa and the femur, or thigh. The fourth 

 part is the tibia, or shank, and the terminal or 

 fifth part is the tarsus, consisting of from one 

 to six joints. Usually the leg of an insect is 

 armed with spines, or clothed with hairs. 

 The spines at the apex of the tibia are usually 

 longer than the others, and receive the* dis- 

 tinctive name of tibial spines, or tibial spurs. 

 The last joint of the tarsus bears one or two tarsal claws, nails, 

 or unguiculi. On the ventral surface of the joints of the tarsus 

 are often ' ' cushions of short hair or of membrane, capable of 



* See page 71 of this volume of Entomological News 



Fig. II. Leg of an 

 insect. 



a, coxa; b, trochanter; 

 c, femur ; d, tibia ; e, 

 tibial spurs ;/, tarsus of 

 five joints ; g, tarsal 

 nails. 



