D. Keilin 455 
r.s., receptacula seminis; s.c., external spiracular scar; s.d., salivary duct; s.gl., salivary gland; 
Tr., tracheal trunks; ut., uterus; v.n., ventral nervous system. 
All the figures except figs. 18 and 22 concern Melinda cognata. 
Fig. 14. Dissection of the anterior portion of the third-stage larva of M. cognata Meisr. 
Fig. 15. Anterior prothoracic spiracle of the second-stage larva, with four papillae, x 240. 
Fig. 16. Internal genital organs of a female emerged from the pupa August 15th, kept in labora¬ 
tory on sugar and honey and dissected November 5th. x 16. 
Fig. 17. Prothoracic spiracle of the second-stage larva, with six papillae. *240. 
Fig. 18. Postabdominal spiracles of the third-stage larva of Sarcophaga sp. probably S. crassi - 
rnargo. x 84. 
Fig. 19. Prothoracic horns with internal spiracle of the pupa of M. cognata. x 134. 
Fig. 20. Postabdominal spiracle of the third-stage larva of M. cognata. x 240. 
Fig. 21. A similar spiracle but of abnormal structure, with one peritreme reduced, x 240. 
Fig. 22. Prothoracic spiracle of the third-stage larva of Sarcophaga sp. probably S. crassimargo. 
x 84. 
Fig. 23. Postabdominal spiracle of the second-stage larva of M. cognata. x 240. 
Fig. 24. A similar postabdominal spiracle but of abnormal structure, x 240. 
Fig. 25. Prothoracic spiracle of the second-stage larva of M. cognata, with five papillae, x 240. 
Fig. 26. Prothoracic spiracle of the third-stage larva of M. cognata. x 240. 
