NO. II NAIADS OF DRAGONFLY GENUS PLATHEMIS—LEVINE 15 
marked by the lateral portions of the sternacostal suture (scs3). The 
resultant composite sclerite is anterolaterally produced into a distinct, 
large, setiferous lobe close to the anterior margin of the coxal cavity. 
The epimeron (ems) is the posteriormost sclerite of the pleuron. It 
extends from behind the coxal cavity to the posterior portion of the 
base of the hind wing. The katepimeron (kem ;), or ventral portion 
of the epimeron, has become completely isolated on the sternal surface 
owing to the intervention of the large poststernum posterior to the 
coxal cavity. This ventral prolongation of the epimeron extends 
almost to the midline of the venter. 
PLEURAL CHAETOTAXY: The entire pleural surface, with the excep- 
tion of the portions adjacent to the pleural sutures, is clothed with 
short setae and spines, whose average length increases slightly posteri- 
orly. In addition, the prothoracic pleura and the areas adjacent to the 
coxal cavities are provided with numerous light-colored setae, which 
are unusual in their extreme length. 
THORACIC STERNA 
PROSTERNUM: The prothoracic sternum (fig. 17) consists of a 
single broad sclerite which represents the fused basisternum and fur- 
casternum. A large partially sclerotized, spiniferous, hemispherical 
area anterior to the prosternum is of secondary origin and not part of 
the definitive prosternum. 
The basisternum (bs), the largest prosternal area, is fused antero- 
laterally with the precoxalia (pr) of the episternum and posteriorly 
with the small furcasternum. Its lateral margins form the sternal 
coxal articulations (cxa;). 
The furcasternum (fs,) is a small transverse area located between 
the prosternal furcal pits (fp1), which are the external manifestations 
of the endoskeletal furcal apophyses. 
MESOSTERNUM: The mesothoracic sternal sclerites (fig. 17) are 
also two in number. 
The basisternum (bsz.) is a medium-sized roughly anvil-shaped 
sclerite in the anteromedian portion of the mesosternum, It is bounded 
anteriorly and laterally by the ventrally prolonged mesothoracic pleura. 
The furcasternum (fs) is a small transverse sclerite situated at the 
posterior end of the basisternum and demarked from it by a spinifer- 
ous ridge that extends between the furcal pits (fpe). 
METASTERNUM: The metathoracic sternum (fig. 17) is composed 
of two sclerites, the basisternum and the poststernum (Asahina, 
1954), which are completely separated by the medioventrally con- 
