( Ixxii ) 



slow and continuous production of every kind of protective 

 I'esemblance, including mimicry." 



In the face of the facts before us this is an explanation that 

 is far more likely to commend itself, than to say with Mr. 

 Bateson,* that "it would be simpler to regard the constancy 

 of the tints of the several species and the rarity of the inter- 

 mediate varieties as a direct manifestation of the chemical 

 stability or instability of the colouring matters, rather than 

 as the consequences of environmental selection for some 

 special fitness as to whose nature we can make no guess." To 

 any one who lias at all studied the subject such an explanation 

 seems quite untenable ; at the same time, it must be allowed 

 that the intermediate varieties are not only rarely found, but 

 ai-e often absent altogether. It must be admitted that they 

 may h;ive been present and are now extinct, but there seems to 

 be no priind Jack reason why discontinuous variation may not, 

 at any rate, have been an appreciable factor in the production 

 of species. 



It is impossible to trace in any way the gradual development 

 of the Coleoptera ; and it is quite impossible to state which 

 was the earliest family. 8ome writers have believed the 

 Rhynchophora to be the most archaic form of (he order: Dr. 

 Leconte, for instance, is of opinion that "the Rhynchophora, 

 being the lowest type of the Coleoptera, are therefore geo- 

 logically the oldest " : f judging, however, from the analogy 

 of the Blatf.ida\ I should be inclined to look for the earliest 

 of the Coleoptera among the less strongly developed genera of 

 the Heteromera, or perhaps among the Malacodermkhv. We 

 have no guide whatever as to the order in which the majority 

 of the families appeared, for in the Rhaitic series and the Lias 

 we find the following fully differentiated : — Carabiihv, Ilydro- 

 phUidiv, Gyriaidiv, Scarahivida', Xitkhdidie, Peltidx, Crt/pto- 

 phaijkhv, Lafhridiidce, Mycetophayklx, Byrrhkhv, AjjhodUdic, 

 Buprestidx, Elateridse, Lampyrulx, 2'elephorula;, Cistelidx, 

 Curcidio7iidx, and C7irysonieli(hr. 



We have before briefly called attention to the fact that the 

 two groups in which mimicking species are most often found 



* /. c, Introduction, p. 23. 



t " Kliyiu;Iiophora of Amuiica, North of Mu.\ieo," liiUoductiuii, \i. vii. 



