224 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 37 



an irregular and complicated life cycle; their complications, however, 

 do not seem to be justified by any necessity (as is shown by the 

 existence of other species belonging to the same order which achieve 

 their aim in a much simpler way). These species, too, exhibit two 

 very different larval phases, but living in different environments and 

 performing different functions and activities. 



15. There are species in which we can observe slightly marked 

 modifications related to particular organs for particular functions in 

 particular environmental conditions ; these modifications can be under- 

 stood as the expression of a limited organism plasticity, or as an initial 

 stage of the modifying process, or also, if we prefer, as the combined 

 result of the two possibilities. 



16. There are species in which the modifications of an organ re- 

 lated to the functions to be performed in particular environmental 

 conditions appear even, though little marked, when the particular 

 characteristics of that biotopos requiring or permitting that behavior 

 are scarcely marked. 



17. There are species in which we can point out a behavior that 

 shows us the process undergone by an organ, a group of organs, or a 

 somatic region, in order to change. 



18. All the modifications considered seem to be included in a class 

 whose representatives have characteristics like those referable to the 

 processes of so-called esogenous adaptation, but which, however, are 

 hereditable and, therefore, susceptible of manifesting themselves in 

 an independent way. 



EXPLANATION OF PLATES 

 Plate i 



GracUaria latifoliella Mill, i, larva of the ist phase, dorsal view of the head 

 (A, antennae; L, labrum). 2, idem, ventral view (A, antennae; /, prelabium; 

 M, maxillae; S, postlabium). 3, larva of aphagous phase, head, dorsal view 

 (A, antennae; L, labrum; A'', mandibles; Q, labial palpi; R, prepharynx; T, 

 tentorium). 4, idem, ventral view (F, spinneret; /, prelabium; M, maxillae; 

 P, maxillary palpi; S, postlabium). 5, portion of the head capsule with a slight 

 indication of mandible. 6, anterior portion of 4, much more magnified. 



GracUaria stigmatella F., larva of the ist phase. 7, head, dorsal view (the 

 same lettering). 8, idem, ventral view (O, anterior portion of the maxilla), 

 9, left antenna, dorsal view. 10, anterior portion of 7, much more magnified 

 (CI, clypeus). 11, mandible, ventral view. 12, anterior portion of 8, more magni- 

 fied. 



Phyllocnistis suffttsclla Zell., larva of the ist phase. 13, mandible. 



