3o6 The Ohio Naturalist [Vol. Ill, No. 1,. 



the sternum, posteriorly with the metathoracic sternum and epis- 

 ternuni and dorsally with the metathoracic scutum. 



The coxa (8) of the mesothoracic leg appears orlobular on its 

 surface, but is really as long as the prothoracic coxa, as will be 

 seen by examining its internal surface. The coxal cavity is much 

 smaller, however, and not circular. The coxa is dovetailed be- 

 tween the trochanter and femur on the ventral surface and articu- 

 lates over them on the dorsal surface. 



The trochanter (9) is fused to the posterior surface of the 

 femur at its proximal end. The femur (10) is flattened dorso- 

 ventrally "and hollowed on its posterior surface from the distal 

 end of the trochanter to the tibial joint. The mesothoracic tibia 

 (11) bears no spine at its proximal end. The articulation should 

 be examined from the inner surface. ( )n its dorsal surface it 

 bears a dense row of bristles and at its articulation with the tarsus, 

 four spines, two ventral and two lateral. The tarsus (12) re- 

 sembles the prothoracic tarsus closely, having first and last seg- 

 ments long and the intermediate ones short. 



By comparing the mesothoracic legs with the prothoracic 

 these latter will be seen to be rotated through 90 degrees on their 

 coxae so that posterior, anterior, dorsal and ventral are reversed. 



The metathoracic spiracle is situated on the hinder and upper 

 border of the epimeron in the membrane connecting this .sclerite 

 with the wing articulations. It is usually tucked under the border 

 of the epimeron. 



THE META-THORAX. 



The metathoracic sternum ( 1 ) forms the floor of this seg- 

 ment between the second and third pairs of legs. Anteriorly it 

 begins on the median line by a narow neck extending between the 

 meso-coxae. The anterior boundary then curves around in front 

 of the coxal cavity and comes into contact with the meso-sternum 

 and ends antero-laterally in contact with the meso-thoracic epi- 

 meron. Beginnnig with the hinder border (jf the coxal cavity and 

 extending to the epimeron is a shallow groove marking ofif a nar- 

 row strip from the anterior border to this sclerite. This is usually 

 described as the mesothoracic epimeron, but is attached to the 

 meta-sternum and cannot be separated from it. The lateral boun- 

 daries of the meta-thoracic sternum are straight and begin at the 

 mesothoracic epimeron and end at the metathoracic coxal cavities. 

 The lateral border bears a shallow groove and the center elevated 

 wall of this groove is in contact with the metathoracic episternum 

 (2) throughout its whole length. Posteriorly the metastermnn 

 forms the anterior boundary of the metathoracic coxal cavity. 



The metathoracic episternum (2) is a long, narrow sclerite 

 lying on the lateral border of the sternum from which it is sepa- 



