312 Annals Entomological Society of America [Vol. XI, 



EXPLANATION OF PLATES. 



Pl.vte XXV L 



Fig. 1. Diagrams to show the attachment of muscles to the cuticida; A, the 

 normal condition; B, after a molt, showing the tendons. 



The oral invagination, longitudinal section. 



The musculature of the pharynx (longitudinal section). 



The oesophagus, cross-section. 



The oesophageal epithelium, normal condition. 



The oesophageal epithelium, premolt condition. 



The oesophageal epithelium, after the formation of the new intima. 



A portion of the crop, cross-section. 



The oesophageal valve, and the transition from the fore-intestine to 

 the mid-intestine (longitudinal section). 



The transition in the musculature from the fore-intestine to the mid- 

 intestine. 



A portion of the first division of the ventriculus, cross-section. 



A portion of the second division of the ventriculus, cross-section. 



Plate XXVII. 



Fig. 13. The musculature of the mid-intestine, showing the transition from the 

 first division of the ventriculus to the second. (The constriction 

 marks the point of separation l^etween the two divisions). 



Fig. 14. The transition from the mid-intestine to the hind-intestine (longitudinal 

 section). 



Fig. 15. The transition in the musculature from the mid-intestine to the hind- 

 intestine. 



Fig. 16. The evagination of the second series of Malpighian vessels. 



Fig. 17. The first stage in the formation of the bladder; the fusion of the four 

 Malpighian vessels of the first series. 



Fig. 18. The second stage in the formation of the bladder; the fusion of the 

 lumina of the two outer vessels. 



Fig. 19. The completed bladder. 



Fig. 20. The entrance of the l:)ladder into the ileum. 



Plate XXVIII. 



Fig. 21. The distal portion of the ileuin, cross-section. 



Fig. 22. Cross-.section of the colon; association of the Malpighian vessels with its 

 walls. The ventral vessel is just coming in contact with the colon; 

 the two vessels of the first series, with the common stem formed by 

 their fusion, and the one vessel of the second series, with the common 

 trunk formed by the fusion of all three, can still be seen. (A nerve 

 separates the two vessels of the first series). The dorsal vessel is 

 already joined to the colon, and the peritoneal sheath is beginning 

 to extend out on each side. 



Fig. 23. Cross-section of the colon; redivision of the trunks. The ventral vessel- 

 trunk has just redivided into three vessels; the dorsal vessel-trunk 

 has already redivided, and the vessels are beginning to migrate 

 around the muscle fibres. 



Fig. 24. Cross-section of colon: the migration of the vessels almost completed. 



Fig. 25. Cross-section of coloii: typical. Note the alternate arrangement of 

 Malpighian vessels and longitudinal muscle fibres. (The upper "E" 

 in this figure should be ''C. M.") 



Fig. 26. Cross-section of colon: the Malpighian vessels are increasing in size 

 and tending to crowd the longitudinal muscles inside. 



