NO. 13 STAPHYLINIDAE BLACKWELDER 23 



parts by the end of the sternopleiiral suture, and fuses with the epi- 

 sterna at its extreme anterior ends. It has no vestiture or sculpture. 

 The mesosternum is prolonged laterally in a narrow piece which 

 forms part of the anterior margin of the coxal cavity and posteriorly 

 in a broad median lobe, the mesosternal process (fig. 3 A, mesp). 

 There are a few scattered very slender setae on the central part, par- 

 ticularly on its caudal margin, and almost the entire surface is densely 

 covered with very fine punctures which appear to bear very minute 

 setulae. On the lateral extensions these punctures are rather sparse, 

 but the setulae are larger and more definite. 



Posteriorly the mesosternum is separated from the metasternum 

 by a narrow sclerite, the spinisternum (fig. 3 A, ss). This is a secon- 

 dary sclerite formed from the intersegmental membrane and united to 

 the mesothorax. It is very narrow medially, expanding somewhat on 

 the floor of the coxal cavities. It is separated from the mesosternum 

 by the spinisternal suture (sss) and from the metasternum by the 

 suture ists. It bears no sculpture or vestiture. 



The pleuron of the mesothorax is larger than either the mesonotum 

 or the mesosternum. It occupies the lateral part of both the dorsal 

 and ventral aspects and forms the processes that project into the pro- 

 thorax for articulation. It is composed of the episternum, the epimeron, 

 and the articulations of the coxa, and bears on its anterodorsal part 

 the base of the elytra. 



The episternum (fig. 3 A, eps. II) is the largest sclerite of the meso- 

 thorax. It is separated from the sternum by the sternopleural suture 

 (sps). Its posterior corner extends to the rim of the coxal cavity and 

 forms an articulation for the trochantin. Its ental projection fuses 

 with part of the epimeron to form the pleural coxal process (cxp). 

 On the ventral surface the episternum is completely separated from 

 the epimeron by the pleural suture (pis), but this suture extends only 

 to the lateral edge and is not continued on the dorsal aspect. Thus 

 the episternum and epimeron are united on the dorsal surface, and 

 this sclerite, the pleuron (pi), forms the anterior projections of the 

 mesothorax. 



The episternum is rather sparsely set with setae, which are short at 

 the prepectal margin and become larger and longer toward the pleural 

 suture. The lateral and dorsal parts, particularly anteriorly, are finely 

 strigulose, the lines being considerably more apparent than the normal 

 very fine markings of sclerotic surfaces. The ventral part is also 

 sparsely set with the minute lageniform punctures similarly to the 

 pronotum. 



