30 OK THE THORAX Or THE BLOW-FLY. 



Fig. 5. Anterior view of prothorax ; pr, pronotum. 



6. Lateral view of thorax. 



7. Posterior view of ditto : ps, postscutellum of the mesothorax ; inph, 



niesophragma formed by the united postscutellum of the mesothorax 

 and the prsescutum of the metathoraxt ; al, alulet ; mm, metatho- 

 racic muscles proceeding to metathoracic entosternum ; ap, apodeme 

 of haltere ; z, narrow margin, probably remains of lateral plate of 

 metathorax ; j, line of junction of thorax and abdomen. 



8. Longitudinal vertical section of thorax in the mesial line, showing lon- 



gitudinal muscles : prov, the proventriculus followed by the chyle- 

 stomach. 



9. The same, with the longitudinal muscles removed, showing : — vm 1 , vm 2 , 



vm 3 , the vertical muscles ; pm, prothoracic muscle inserted in the fore 

 coxa ; mm, metathoracic muscle to entosternum. 



10. Transverse vertical section of thorax, showing muscles. 



11. Horizontal longitudinal section of ditto. 



12. Internal view of a portion of the thoracic cavity, showing :—pm, the 



muscle of the fore coxa ; m*, small muscles connected With the wing 

 beneath the parapteron. A strong process, g, of the prsescutum is 

 seen to bridge across the humerus without touching it. 



13. The pupa of the Blow-fly': o, the compound eyes ; pa, the prothoracic 



dorsal appendages. 



Plate II. 

 Pig. 1. Pupa of Crane-fly. Anterior portion, showing :—pa, the prothoracic 

 appendages; mes, the posterior portion of the mesothorax (upon 

 removing the integument at this part, the postscutellum of the me- 

 sothorax (ps, fig. 2) of the imago is revealed) ; met, the metathorax ; 

 w, w', the anterior and posterior wing-cases. 



2. The' thorax of the Crane-fly. The plate, ps, between the halteres, cor- 

 responding to the posterior wall of the thorax of the Blow-fly, is 

 shown to be mesothoracic, i. e. the mesothoracic postscutellum as it is 

 developed beneath the mesothoracic integument of the pupa. 



3 & 4. The anterior and posterior wing-cases of the pupa of the Crane- 

 fly. The haltere is shown in course of development within the latter. 



5. Longitudinal vertical section of the thorax of the Humble-Bee : ps, the 



postscutellum of the mesothorax, to which the muscles, m, are attached. 



6. The thorax of the same, showing the reduced extent of the metathorax ; 



col, the collar ; a, its posterior angle ; sp*, spiracle of fifth segment. 



7 & 8. Figures adopted from Packard, showing the two stages in the deve- 

 lopment of the pupa of the Humble-Bee. In the latter the thoracico- 

 abdominal constriction is seen to include the fifth segment (i) with the 

 thorax : sp*, the spiracle of the fifth segment. 



9. The thorax of Liparis salicis. 

 10. Longitudinal vertical section of the thorax of Liparis salicis : parts the 

 same as in fig-. 5: 



t Consult anted,, p. 28. 



