548 The University Science Bulletin. 



surface of this flangelike part forms a pocket or fold, called by 

 Martlatt (1895 » a pseudo-sheath, which receives and partially pro- 

 tects the mandible. It is connected to the mandible, as in the 

 maxilla, by a chitinous arm of the stylet. It may be possible that 

 the mandibular sclerite is comparable to the sclerite found in lower 

 orders of insects, which is termed the trochantin of the ynandible by 

 Comstock and Kochi (1902) or the basi'mandibiihe by Crampton 

 (1921). 



THE THORAX. 



The prothorax, as is shown in (pi. LVI, fig. 6) is weakly attached 

 to the mesothorax, but is closely associated with the head, since it 

 invariably comes off with the head when the latter is removed from 

 the body. The mesothorax and metathorax, however, are firmly 

 joined and the sclerites somewhat overlap on the dorsal surface, 

 making identification of the sclerites rather difficult. 



There is no evidence of cervical intersegmentalia in Lepyronia, or 

 of any structures which might suggest them. The cephalic surface 

 of the prothorax appears to fit directly against the caudal surface of 

 the head without any intervening structures which might be termed 

 these sclerites. 



THE PROTHORAX. 



The notum (pi. LVII, fig. 1) of the prothorax is a large, fiat 

 sclerite occupying the entire dorsal surface of this segment. It is 

 twice as long as wide and has its short, lateral margins nearly paral- 

 lel. The anterior margin is broadly rounded. The posterior margin 

 is deeply emarginate on the produced middle third. The edges of the 

 notum are greatly deflexed so that they unite with the pleuron on 

 the ventral surface. 



From a cephalic aspect of the pronotum (pi. LVII, fig. 5) can be 

 seen a narrow sclerite, which probably corresponds to the sclerite in 

 the Cicada termed by Taylor (1918) the pretergite. Mesad this 

 sclerite is very narrow, but laterally it widens out to four or five 

 times its median width. It lies at right angles to the notum and is 

 connected to the pleuron by a tapering projection. The pretergite 

 is not as heavily chitinized as the notum and pleuron. 



The pleuron (pi. LVII, fig. 3) of the prothorax is closely joined 

 to the deflexed part of the notum without a distinct line of connec- 

 tion. It is divided longitudinally by a very indistinct pleural suture 

 into two sclerites, the epimeron and episternum. The episternum, 

 the anterior of the two, is roughly rectangular in shape and about 

 twice as long as wide. The epimeron is slightly larger than the 



