40 Annals Ejitomological Society of America [Vol. IX, 



composed of four subsegments, for, as already stated, Audouin 

 appears to have believed that the thorax consisted of three 

 simple segments. 



Schiodte, '56 and Winslow, '62, followed Audouin's ideas 

 and believed that the thorax was composed of but three seg- 

 ments, the pro-, meso-, and metathorax. 



Packard, '80, seems to have regarded the thorax as made up 

 of three simple segments, but his interpretations and methods 

 of homologizing the thoracic sclerites in the insects of the 

 different orders which he studied, are incorrect. The homologies 

 of the thoracic sclerites will be discussed further on. 



Miall and Denny, '86, in their book on the Cockroach, 

 considered that the thorax was composed of three segments 

 and suggested that the chitinous plates at the base of each 

 leg in the roach (i. e. epimeron, episternum, trochantin, etc.) 

 represent "two basal leg joints, which have become adherent 

 to the thorax," although in other cases they state that they 

 belong "to the thorax and not to the leg. " 



If these sclerites at the base of the leg in the roach represent 

 leg "joints," there would probably be more definite traces of 

 these joints in other insects, especially as the leg is such an 

 important appendage. In the embryo of the cockroach the 

 coxa is apparently the only basal leg segment present and there 

 are no indications of other leg segments which have or which 

 might become adherent to the thorax. This is true for other 

 insects as well as for larvae and primitive forms. Moreover, 

 it is improbable that such leg segments, if present, would form 

 the lateral wall of the segment or pleuron which Miall and 

 Denny thought was the case in the Mole Cricket. It seems 

 more probable that the basal leg "joints" or segments would 

 remain in place and not move up into the pleural region. Borner 

 considered the pleural plates as part of the sternum, but later 

 with Henneguy, thought that they were plates of the basal 

 leg segments. 



Hagen, '89, advanced the theory that each thoracic segment 

 was composed of three subsegments, each subsegment bearing 

 a characteristic appendage. The anterior he terms the leg 

 bearing, the next following the wing bearing, and the posterior, 

 the spiracle bearing subsegment. Some of the subsegments 

 develope more than others. On the prothorax of Strepsiptera 

 and agrionids, he finds traces of "wings. " 



