NO. lO MORPHOLOGY OF GNATIIOTRICHUS SCHEDL 35 



Scutum. — The scutum (fig. i6, Stu) is represented as two slightly 

 chitinized lobes which are anteriorly fused with the prescutum. The 

 posterior ends are free and lie under the scutellum. A long slender 

 pleural hook (c) originates near the extreme lateral angle. 



Prescutum. — The largest area of the mesonotum is occupied by 

 the triangular prescutum (fig. i6, Psc). Externally it forms with 

 the scutellum a smooth continuous plate. The inner side consists of 

 two large and shallow excavations which are surrounded by heavily 

 chitinized ridges. The median ridge is anteriorly divided by two 

 closely placed sutures. Obscure remainders of these sutures are also 

 visible externally and on the scutellum. The extreme anterior corners 

 of the prescutum are produced into two prominent hooks which may 

 correspond to Hopkins' " Lateral arm of prephragma and prescutum " 

 or Korschelt's " Zapenfortsatz des Mesonotums," or Berlese's " clavic- 

 ola." The clavicola (b) is hinged in parts of the pleural claviculas. 

 At a short distance behind the clavicola is a well developed prealar 

 process which embraces the third axillary of the elytra. On the 

 anterior two-thirds of the prescutum, numerous small punctures are 

 visible externally and near the lateral margin occurs a single row of 

 minute hairs. 



The prephragma and the postscutellum are not represented by sepa- 

 rate plates. Remainders of the former are probably the wide anterior 

 ridge of the prescutum. 



Mesopleura. — The mesopleura are distinctly defined from the ter- 

 gum and sternum. The largest area of each is occupied by the epi- 

 sternum (Eps) which is a strongly chitinized plate, elongate, with the 

 lateral dorsal area smooth and with a fine pubescence on the lateral 

 ventral area. A narrow strip in front of the episternum, which is 

 defined externally by a suture, and a continuation of it towards the 

 ventral posterior angle of the episternum, may represent the preepi- 

 sternum. Dorsally the preepisternum is produced into the clavicolar- 

 disk. Under the ventral half of the episternum projects a narrow 

 plate, the epimeron (Ep). Preepisternum and epimeron are struc- 

 tureless but the latter bears on its posterior margin a row of fine hairs. 



Mesosternum: Presternum. — A narrow ridgelike plate which is 

 fused with the preepisternum (fig. 16, Pr) of the pleura represents 

 the presternum (Pst). The rest of the sternum is externally defined 

 from this by a suture. Internally the suture is obsolate. 



Sternum. — The sternum (St) is a rectangular plate with its poste- 

 rior side produced into an angle, externally fused with the sternellar 

 area or intercoxal process (Stl) but internally defined by a suture. 

 The outer surface is smooth and bears a row of bristles and also a 

 few punctures. 



