THOEAX OF THE BLCTWVFLY. 29 



arrived at through a series of errors, and that I can scarcely 

 hope that all my observations will prove exceptions to the 

 general rule. 



DESCRIPTION OF THE PLATES. 



All the illustrations are necessarily much magnified. 



The parts of the thorax are designated in accordance with my own view of 

 their relations, except where indicated in brackets, and are lettered the same 

 throughout the series of figures, viz. : — 



h. The humerus, prs. The prtescutum of the mesothorax. 



scm. The scutum of the mesothorax. 



scm'. ,, ,, metathorax (not found in the Blow- fly). 



scl. The scutellum of the mesothorax. 



scl'. „ „ metathorax (not found in the Blow-fly). 



con. Lateral processes of the presternum (Lowne's condyles). 



epis. The lateral plates (episterna) of the prothorax. 



sp. The anterior (prothoracic) spiracle. 



sp'. The posterior (mesothoracic) spiracle. 



sp*. The spiracle of the fifth segment. 



coon, cox', cox". The anterior, intermediate, and posterior coxse. 

 par. The parapteron (Lowne's anterior lateral plate of the mesothorax). 

 epim. The epimeron of the prothorax (Lowne's cornua). 

 st. The sternum of the prothorax. 

 st'. „ „ mesothorax. 



epis'. The episternum of the mesothorax (Lowne's posterior lateral plate). 

 x. Uncertain (Lowne's lateral plate of the metathorax). 

 epim'. The epimeron of the mesothorax (Lowne's metasternum). 

 ps. The postscutellum of the mesothorax (in PI. I. Lowne's dorsal plate of 

 the metathorax). 

 ps'. The postscutellum of the metathorax (not found in the Blow-fly). 

 Im and vm. Longitudinal and vertical muscles of the mesothorax of the Blow- 



fly (Pi. L). 



rn.es. Mesothorax (PI. II.) ; met. Metathorax (PI. II.). 

 i. The dorsal plate of the fifth segment (PI. II.;. 

 m. The longitudinal muscles of the mesothorax (PI. II.). 

 m'. „ „ metathorax (PI. II.). 



Plate I. 



Eig. 1. Dorsal surface of thorax of Blow-fly. 



2. Ventral surface of ditto : /, the cephalothoracic foramen ; ac, aceta- 



bulum of fore leg ; hal, the haltere. 



3. Entosterna of meso- and metathorax, side view. 



4. The same, from above. 



