1865.] 215 



seventy distinct species of the same genus are they always arranged in 

 the same pattern, subject only to the very slight variations noticed 

 above? Why — as is most likely the case — should Nature have ser- 

 vilely repeated the same monotonous Colorational Pattern throughout 

 the whole genus Ichneumon, which probably comprises at least 500 

 species, and is numerously represented on both sides the Atlantic "' 

 Why in allied genera do we find curious modifications of the same fun- 

 damental pattern, and not entirely new and original patterns ? Why 

 in allied genera do we find none entirely without bullae, and none with- 

 out the spots i^and G .^ Why is the lociis of the spots i^ and G ab- 

 solutely invariable throughout Ichnemnotiixfse and Braconidse? If 

 these seven spots could answer any possible utilitarian purpose, we 

 might say that they occur throughout Ichiuumon, because the peculiar 

 habits of that genus require them for that purpose. But they are mani- 

 festly mere ornamental designs, in no possible respect necessary or use- 

 ful to the individual Ichneumon, any more than the numerous small, 

 pale spots on the bodies of many adult Fallow Deer, which occur also 

 in the fawn of the common North American Deer, are necessary or 

 useful to the individual Deer. 



To my mind, there can be but one satisfactory answer to all the 

 above questions. There must be a close genetic connection between 

 all the species of the genus Ichneumon, and a more remote genetic con- 

 nection between that genus and the other genera of IchneumonklaR. 

 " Community of descent," says Darwin as interpreted by Lyell, " is the 

 hidden bond which naturalists have been unconsciously seeking, while 

 they often imagined that they were looking for some unknown Plan of 

 Creation." (Antiq. Man. p. 412, Amer. ed.) Let him, who refuses to 

 accept this solution of the enigma, offer a better solution himself. 



Siquid novisH rectius istis, 



Candidas imperii ; si non, his utere incum. 



But do not let him utter sonorous common-places, about carrying out 

 the Plan of Creation and completing the System of Nature, and then 

 fancy that he has explained facts, when in reality he has only re-stated 

 them in general terms. 



Rdik Isi.ani>, Illinois, Xov. 16, 18(55. 



