62 ON THE ANATOMY OF THE FLY. 



DESCRIPTION OP PLATE V. 



Fig. 1. An anterior view of the thorax with the head removed, show- 

 ing the cephalo-sternum and condyles in situ, x 8 diam. 



Fig. 2. A vertical section of the thorax behind the wings, showing the 

 manner in which the wings are united to the thorax, the meso -sternal 

 ento-thorax, and para-pleura, together with the arrangement of the 

 thoracic muscles. The non-striated longitudinal muscles are distinguished 

 from the striated muscles by a difference in their tint, and the small 

 space occupied by the viscera is well seen; it is marked by a blue tint. 

 X 8 diam, 



Fig. 3. The meso-thorax seen from above, showing its division into 

 four distinct portions, as well as the insertion of the wings and winglets. 

 X 6 diam. 



Fig. 4. A posterior view of the thorax, the abdomen being removed 

 showing the meta-thoracic tergum a, divided like the meso-thoracic 

 tergum into four parts ; i, is the ventral portion of the first abdominal 

 segment ; and e, c, represent the lateral portions of the meta-sternum. 

 The winglets, halteres, posterior thoracic spiracles, and the posterior 

 thoracic opening are shown, x 6 diam. 



Fig. 5. A lateral view of the thorax, in which a is the meso-sternum, 

 b, the anterior lateral plate of the meso-thorax, and c the side of the 

 meta-sternum. The other portions will be easily understood by reference 

 to the text, X 6 diam. 



Fig. 6, A longitudinal vertical section of the thorax, showing the dis- 

 position of the main trachea, the ento-thorax of the meso and meta- 

 sternum, and the great muscles of the back, x 6 diam. 



Fig. 7, The under surface of the thorax, showing the four sterna, and 

 the openings with which the coxse are articulated, x 8 diam. 



Fig. 8. The lower half of the thorax, seen from within, showing the 

 four sterna with the ento-thoracic processes, a Eepres^nts the meso- 

 sternum ; 6, 6, the lateral plates of the meso-thorax ; and c, c, portions of 

 the meta'-sternum. x 8 diam. 



Fig. 9. The cephalo-sternum, condyles, and a portion of the pro-sternum, 

 seen from within, X 15 diam. 



Fig. 10. The pro-tergum, seen from within, x 15 diam. 



Fig. 11. A portion of the flank, "seen from within, showing the 

 insertion of the wing and para-pleura, a, Part of the meso-sternum ; 6, 

 episternum of meso-thorax ; c, episternum of meta-thorax ; c?, side of 

 scutellum ; e, part of the dorsum of scutellum, x 8 diam. 



Fig. 12. The insertion of the wing, from without, showing the wing, 

 pivot and socket, a, The ampulla ; b, support of the winglets ; c, the 

 sub-costal nervure, seen in section, x 25 diam, 



