GENERAL DISCUSSION. 



83 



its structure. So, then, determinate variation in the direction of loss is 

 widespread. That its evolutionary effect is not greater is the result of 

 natural selection, because so great a difference as actual absence is more 

 likely to have selection value than small differences, and because it is often 

 opposed by the activity of determinate selection towards some constructive 

 end. Thus in Hippodamia convergens variations of loss probably arise in 

 regions where determinate variation is building up a pattern of confluence. 

 Such negative variations would serve merely as a slight and easily sur- 

 mounted obstacle. 



This hypothesis makes it unnecessary to resort to such questionable 

 hypotheses as use-inheritance or panmixia, to explain the decadence of 

 unused organs such as the eyes of cave animals. If use-inheritance or 

 panmixia be accepted to explain these cases, then no useless organ should 

 persist. This persistence of some useless organs, such as the anal spine 

 in some moth larvae, offers no difficulty to the hypothesis of loss of deter- 

 miners, for the frequency of this loss would depend on the nature of the 

 determiner-complex and on the presence or absence of opposed lines of 

 determinate variations. 



It is not uncommon to find two spots which are confluent in some speci- 

 mens showing in others, where there is no confluence, pointed extensions 

 each directed toward the other. Such may be seen in many of the figures. 

 It is abortive confluence. This indicates that confluence is not the pig- 

 mentation of a third unit, a connecting bar, between the two spots in 

 question. It is rather an extension of pigmentation from the spot in a 



Anisostirta. 



1. strigata. 



a. var. bitrianjruhiris. 

 Naemia. 



2. seriata. 



ft. Form A. 

 It. Var. litiginosa. 

 Macronaemia. 



3. episcopal!*. 

 Paranaemia. 



4. vittigera. 

 Megilla. 



f). maclllata. 



a. snbsp. lloridana. 

 Ceratomegilla. 



ii. ulkei. 

 Eriopsis. 



7. connexa. 

 Hippodamia. 



8. glacialis. 



. Var. G. 



9. convergens. 



a. Var. obsoleta. 



ft. Var. rnoesta. 



c. Var. quinquesignata. 



(I. casoyi, etc. 

 e. Var. -1. 



10. spuria. 



a. Var. complrxn. 

 ft. Var. 1,4 + 5,6. 

 c. Var. liiieatu. 



11. tredecimpunctata. 



a. Var. signata. 

 ft. Var. spissa 

 c. Var. boreal is. 



12. lengi. 



13. bowditchi. 



14. oregonensis. 



KEY TO TABLE 20. 



Hippodamia. 



15. cockfivllii. 



16. dispar. 



17. parenthesis. 

 is. apicalis. 



a. Var. i + 3, 1+2 

 + 5 + 6 + a. 



19. americana. 



20. simiata. 



21. falcigera. 

 Neoharmonia. 



22. ampla. 



23. venusta. 



24. notulata. 

 Coccinella. 



25. .julmsoiii. 

 2(i. perplexa. 



ft. Var. subvcrsa. 



27. novemnotata. 



". Var. franciscana. 

 ft. Var. confluent;!, 

 c. Var. californica. 



28. californica. 



'(. melanocollis. 



29. tricuspis. 



30. transyersoguttata. 



31. monticpla. 

 :s2. difflcilis. 



33. prolongata, 



34. suturalis. 

 Cyckmeda. 



35. sanguinea. 



36. rn mida. 



37. ater. 

 Olla. 



38. abdotninalis. 



a. Var. semilunaris, 



39. plagiata. 



Adalia. 



40. bipunctata. 



n. Var. berbsti. 



ft. Var. quadrimacu- 



lata. 

 <. Var. - 



41. frigida. 



a. Var. parvnla. 

 ft. Var. immaculata. 

 c. Var. humeralis. 



42. Annectans. 



a. Var. liumeralis. 

 ft. Var. transversal is. 

 Harmonia. 



43. picta. 



n. Var. blanchardi. 

 ft. Var. concunator. 



44. hudsonica. 

 Agrabia. 



45. cyanoptcra. 

 Anisocalvia. 



4(i. duodecimmaculata. 

 47. quatuordecimguttata . 



a. Var.- . 



ft. Var. - . 

 Analis. 



4S. quindecimmaculata. 



49. mali. 



50. ratbvoni. 



51. lecontei. 

 Epilacnna. 



52. bo real is. 



. Var. 1,2,3+ r,4. 

 5 + 6 + v, 7. 



53. toweri. 



54. corrupta. 



a. Var. juncta. 



55. mexicaua. 



