10 LAEV^ OF THE PEIONIN^. 



beneath each of these median dorsal areas is a lateral dorsal area. This 

 is large and trapezoidal on the prothorax, narrow and elongate on 

 mesothorax and metathorax. Ventrad of this latter area is the 

 transverse lateral zone. On this area on the prothorax in some 

 species {Mallodon) a group of chitinous spines occurs, as also a teat- 

 like tubercle or projection. The lower limit of the lateral zone is 

 defined by the pleural suture separating it from the hypopleurum 

 adjacent to and partly surrounding the coxal lobes. The hypopleu- 

 rum is relatively small in all thoracic segments, probably crowded 

 by the development of the coxal lobes. The region (PL II) of the 

 prothorax consisting of presternum, ensternum, and sterneUum, is 

 rectangular. The presternum is large, somewhat enveloping the 

 triangular eusternum, from which it may or may not be distinctly 

 separated by a curved suture. The eusternum is separated by a 

 straight transverse suture (at the extremities of which he the coxae) 

 from the sterneUum. The sterneUum is narrow, transverse. On the 

 mesothorax and metathorax a transverse suture divides the ventral 

 region into two folds, the anterior of which is the eusternum and the 

 posterior the sterneUum, both folds being narrow and transverse. 



The terminology of the thoracic segments as given here is as yet 

 only provisional. It is merely homologized from that of the abdomi- 

 nal segments and has not been worked out thoroughly by a study 

 of the muscular structure. 



There are two thoracic spiracles. One of these is situated between 

 the prothorax and the mesothorax, probably belonging to the meso- 

 thorax; the other, smaU and rudimentary, is placed on the meta- 

 thorax. The first thoracic spiracle is always larger than those on the 

 abdominal segments. 



The legs are short and conical and consist of five joints, the fleshy 

 coxal lobe considered as the basal joint. The trochanter is very 

 smaU and often invisible from the outer side; the femur and tibia 

 are cylindric, about as broad as long, and often armed with a circlet 

 of short, stiff hairs. The tarsus is represented by a single long, 

 slender, more or less chitinous spine. 



The abdomen (PI. II, fig. 5) consists of ten segments, eight of 

 which bear spiracles. The first seven segments are similar in struc- 

 ture. The tergal and sternal areas are developed into a large, fleshy 

 protuberance, the ambulatory ampulla (Perris) . This structure, vari- 

 ously modified throughout the longicorns, is uniform in the Prioninse, 

 slightly more rugose but differing Uttle from the remaining body 

 texture, those in some genera differing by the presence of chitinous 

 asperities on the ampuUse. The dorsal ampullae bear two transverse 

 impressions; the ventral ampullae, one. 



Surrounding the ampullae on all except the last two segments is 

 an eUiptical area, protruding or swollen lateraUy. The dorsal of these 

 surrounding areas has been named the parascutal lobe (Boving) and 



