OF Tin: AMAZON VALLEY. 507 



Bees, Wasps, and other ITymenoptorous aiul Di{)torous insects. Tlie parallelism In'twcen 

 these several iornis and their geoii:ra])hical relations have not yet, 1 helieve, lieen inves- 

 tigated. The resunihlanees seem to l)t' more closely spccilic in tropical countries than 

 in Europe ; and I think it likely that the counterfeits in hi^h latitudes may not always he 

 found in company with their models, it is possil)le the i;'eot;raphical relations hetween 

 the species coiu-erned may have; l)een disturhed hylhe ureat elimatal and L^'eoloi^ical 

 ehaiiii'es which have occurred in this ])art of the worhl since the dale when they tlrst 

 came into existence. 



Not only, however, are Ilellcouida; the ohjects selected for imitation; some of them 

 are themselves the imitators ; in other words, they countin-feit eacii other, and this to a 

 considerahle extent. S])ecies l)(dom;-imc to distinct i^enera have hcen confounded, owinu' 

 to their heini,' almost identical in colours and markings; in fact, many of them can 

 scarcidy he distinguished except hy tlunr generic characters. It is a most strange cir- 

 cums1anci> connected with tliis family, that its two sections, or suhfamilies, have heen 

 miiiii'led together hy all authoi's, owiiii;' to the very (dose reseml)lance of many of their 

 species. Analogies hetween the two sLd)raniilies have heen mistaken for alllnities. It is 

 sometimes dillicult to understand in these cases which is the imitator and wliicdi the 

 imitated. We have, however, generally a sure t(\st in the one set cxhiliitinu' a departure 

 from tlie normal style of colouring of tlieir congeners, whilst tiie other are conlorniahle 

 to tlieir generic types. The species o[' Xtqteorjencs are, hy this criterion, evidently all 

 imitators of Itliom'ue; they are also rare insects, like the Lcphdidcs. The mimetic 

 species of ndicoiiins must h(>, for the same r(>as(Hi, imitators. 



These imitative resemhlances, of which hundreds of instances could he cited, are full 

 of interest, and fill us with the greater astonishment the (doser we investigate them ; for 

 sonie show a minute and palpahly intentional likeness wiii(di is perfectly staggering. I 

 have found that those features of the portrait are most attended to hy nature whicdi pro- 

 duce the most elfective deccj)ti(jn when the insects ar(> seen in nature. The faithfulness 

 of the resemhlance, in many cases, is not so striking Avlu'u they are seen in the 

 cahinet. Although I had daily practice in insect -collecting for many years, ami was 

 always on my guard, T was constantly heing deceived hy them when in the woods, it 

 may he asked, why are mimetic analogies so numerous and amazingly exact in insects, 

 whilst so )"are and vague in tin* higlier animals*? The oidy answer that F can suggest 

 is, tiial insects have ])erhaps attained a highei' den'ree of specialization, after their type. 

 than most other chisses : tiiis seems to he shown hy the jierfection of their adai)ti\(' 

 structures and instincts. Their heing more numerous and striking in trojiieal thrmin 

 temj)erate countries is perhaps attril)utahle to the more active com])etitive lile, and the 

 more ra])id successicm of their gen(>rations, in hot than in cold c()untries. 



It is not dillicult to di\iue the nieauing or final cause of these analogies. 'When we 



* Two instances of mimicry in hirds, ([uitc as wonderful as those hetween l^fpfa/is anil Ithomia, have just heen 

 communicated to me by mj' old travellinf; companion, Mr. A. 11. Wallace. He has o1)served two species of ()riu/ii/cc 

 (perverted from the normal facies of the family) attendant on two spci'ies o( Me/iji/iiii/u/a', and miinickin;; them in the 

 most curiously minute way in colours ami in general figure. The associated pairs inhabit sej)arale islands, as t'ollows : — 

 — L Bourou, Mimetii (Oriolidw) Buuro'cn^in, Trojiiilorliynchus (Mc/iji/iai/idd-), n.^). ; I. Ci'vain, Mi me la Forslini, 

 Tropidurhijnchus suhcarinatus. 



