xxxiv Contents. 



of Deilephila show a nearer form-relationship as imagines than as 

 larvae, 454. Systemy not only the expression of morphological 

 relationship, 455. Varieties; incongruence the rule; seasonal dimor- 

 phism ; climatic varieties; dimorphism of caterpillars ; local varieties 

 of caterpillars, 456. Result of the investigation, 458. Causes of 

 incongruence, 460. A phyletic vital force does not explain the 

 phenomena, 461. This force is superfluous, 464. 



III. 



Incongruences in other Orders of Insects, p. 481. 



Hymenoptera. The imagines only possess ordinal characters, 481. 

 Double incongruence : different distance and different group-forma- 

 tion, 483. Diptera, 488. The larvae form two types depending on 

 different modes of life, 489. The similarity of the grub-like larvae 

 of Diptera and Hymenoptera depends upon convergence, 494. 

 These data again furnish strong arguments against a phyletic vital 

 force, 496. The tribe Aphaniptera, 498. Results furnished by the 

 form-relationship of Diptera and Hymenoptera, 499. Difference 

 between typical and non-typical parts transient, 501. 



IV. 



Summary and Conclusion, p. 502. 



First form of incongruence, 503. Second form of incongruence, 

 506. General conclusion as to the elimination of a phyletic vital 

 force, 511. Parallelism with the transformation of systems of 

 organs, 513. 



Appendix I., p. 520. 



Additional notes on the Ontogeny, Phylogeny, <fcc., of Caterpillars. 

 Ontogeny of Noctua larvae, 520. Additional descriptions of Sphinx- 

 larvae, 521. Retention of the subdorsal line by ocellated larvae, 529. 

 Phytophagic variability, 531. Sexual variation in larvae, 534. 



Appendix II., /. 536. 



Acr<za and the Maracuja butterflies as larvae, pupae, and imagines, 

 536. 



Explanation of the Plates, p. 546. 



