ENTOMOLOGIST AND BOTANIST. 



335 



Nmtli Amiriciv, of very nuniiroiis diiitinct siiccies of Ceci- 

 dumijitt, ol Sciara, of Ceratopogon, of Nematut, and of 

 lirnrhinus. 



Upon till- siimti principle 1 ^ti'ongly incline to bflivve tliat 

 till! 17-yciir form of the I'erioiliciil Cicada (C. eeptemtlecim, 

 lAtm ) is 11 ilistinct species from llie i:j-year form (C. (ic- 

 dccim, Kiley), aUhouKli it has Ijeen impossible for nic, on tlie 

 closest examination of very numerons specimens, to detect 

 any S])ecillc difference between tliese two forms.* It is very 

 true that the 13-year fomi is coDlliied to tlie more southerly 

 resions of tlic United States, while the 17-year form is 

 generally, but not imivcrsally, jjcculiar to the Northern 

 States; wlience it has been, with some show of plausibility, 

 inferred that the U-year form is nothinf; but the 17-year form 

 accelerated in its metamorpliosis by the inlluenee of a hot 

 southern climate. I5ut as these two forms interlock and 

 overlap each other in various localities, and as it frenuently 

 liapi)cns that particular broods of the two forms come out in 

 the same year, we shouUl certainly ex|>ect that, if the two 

 forms belonged to the same species, tliey would ocasionally. 

 intercross, whence would arise an intermediate variety hav- 

 ing a periodic time of It, 15 or IC. years. As this does not 

 ttpl>ear to have taken place, but, on the contrary, there is a 

 pretty sharp dividing line between the habits of the two 

 tbrms, without any intermediate grades of any consequence, 

 I infer that the internal organization of the two forms must 

 be distinct, altliough externally, when placed side by side, 

 they arc exactly alike. Otherwise, what possible reason 

 could there be for one and the same species to lie under- 

 ground in the larva state for nearly 17 years in one county, 

 and in the next ailjoining county to lio underground in the 

 larva state for scarcely 13 years V 1 presume that even (he 

 most bigoted believer in the old theory of species would 

 allow that, if it can once be proveil to his satisfaction that 

 two apparently identical forms are always structurally dis- 

 tinct, wliether in their external or in their internal organiza- 

 tion, they must necessarily be distinct species. 



On the other hand, I llrmly believe that many perfectly 

 distinct forms, which at one time passed current, or which 

 even now pass current, as true species, are in reality mere 

 dimorphoua forms of one and the same species. We lind a 

 goodcxampleol this in the dimorphous c Cynips, (l.aciculala, 

 O. S., which has been alnady treated of at great length. 

 We lind another good example of the same thing in Cicada 

 Caasinii J <J , Fisher, which is sidliciently distinct from the 

 rerioUical Cicada to have been classified as a distinct siiecies , 

 and yet ni!Ver occurs except in the same year and in the same 

 locality as Ibis last, anil what is more extraordinary still, is 

 found not only along with the 17-year form (C. itptemdccim) , 

 but also along with the i:)-year form (C. Iredecim) . Now, if 

 C(ts.iinii were a distinct species, and not, as 1 believe it to be, 

 a mere dimorphous form of C. scplemdecim and C. Iredecim, 

 llie chances are more than a million millions to one against 

 its always coinciding with the other two forms, not only as 

 to tlie particular locality but as to the particular year of its 

 appearance. 



It has been urged in opposition to the above view, by an 

 entomological friend of gn^at scientillc eminence, that di- 

 niorphous forms only appear in one sex. 1 believe that they 

 very freipieiitly appear in both se.ves; but of course, in the 

 Miiijority of instances, (hey are then very naturally accepted 

 asdi.^tinct species Suppose, for example, that there were 

 smh a thing as a ^f as well as a '.■> Papilio Glaucus, Linn., 

 who would then ever have dreamt that Glaucus was a mere 

 diinori>hoiis C form of Turnuil It was jirecisely the absence 

 of the ,f form corresponding to v GlaucM, that lirst led 

 entomologists to doubt the possibility of Gtaucut beluga tnie 

 hona Jide species; and it was upon similar grounds that Mr 

 Wallace established the existence of several such dimorphous 

 and trimorphous Tapilios in the Malay Archipelago. But 



in point of fact there do really exist, and have long been 

 known to exist, many dimorphous forms which are not con- 

 lined to a single sex It is only necessary lo mention, as 

 good illustrations of such a staite of things, the long-winged 

 anil .-hort-winged forms common to both sexes of many 

 Ortliopterous, lleteropterous and llomopterous genera, such 

 as GnjllijIaliKi, Ncmoliiui, Cijnipa (Teras), Pezomachu; 

 Churciiis, ligdromctra, Gcrrin, lelia, Proslemma, PjTrhucoria, 

 Pterotmctus, Itnichomorpha, Dctphax, etc. Nor are such 

 phenomena peculiar to the Class of Insects. Mr. Wallace, 

 in his admirable Taper On Ihc Malayan PapilionidiC, remarks 

 that he "met w lib one case of a bird, a species of i.ory (Eat 

 fuscata, lilytlu), clearly existing under two forms, since 

 !<o//j«c«sof each were obtained from asingic Hock." (TVons. 

 Linn. Soc. xxv, p. 10 ) And the albinism and melanism 

 which are so common among many mtimmals and birds, and 

 which may be considered as moililled types of dimorphism, 

 are well known not to be conlined to either sex. 



On till- whole, I think we may conclude with perfect safety, 

 that tlie species of insects as limited in the books are merely 

 provisional; that on the one band many forms which are in 

 reality spLcilically distinct are confounded together by the 

 closet-naturalist, because his cabinet specimens of the 

 imagos exhibit no distinctive charactei's whatever; and that 

 on the other hand many forms, which are in reality merely 

 dimorphous types of one and the same speciea, are pro- 

 nounced by him to be distinct sjiccies. 



Of course, if we choose to assume that no two species can 

 possibly be distinct unless they are externally distinguishable 

 in the imago, and that all forms that arc externally dislin- 

 giiishablc in the imago are distinct species, then eveiytbiiig 

 that has been said above will go lor nothing, ami the whole 

 doctrine of dimorphous forms, and also, 1 might adil, of 

 secondary sexual distinclions, falls to the ground, lint— 

 luckily for the intere.stsof truth— a.ssumptions are not |irools; 

 and even, if we assume that the sky is going to fall to-mor- 

 row, it by no means follows that we shall then catch any 

 considerable number of larks, 



[To he continual. ] 



• Kiir an oiccllent BUtemoiit of Ihc facU licarlnR upon lhi« curious cniinlion, 

 sv,al'a|H;r by Mr. Bili-y, Hit- Slato EiiUmioloKut ol Mi«.ouri, ."' "o- ■• "J 

 llic AmI'IUOan Entomoi-ooist, and a »lill more coiiiptcto ouo in liw Kinl 

 Auuual ItoiHirt. 



An Ke.kctkicm- Insixt.— You tiro well ac- 

 iiuaiiited willi Uie lii.'itoi-y and i>ro[)crties of the 

 liaia lovpcdo tiiul Gi/mitotus eleclricm; but 1 

 dai-e aver have no idea tliat any insect yossesse.s 

 tlieir extraordinary powers; yet I can assure 

 you, upon sood autliority, tliat liediu-ius ncrra- 

 tiis, coinnioiily liiiowii in the West Indies by llie 

 name of the " Whocl-biig-," can, like tlieiu, 

 coinnuiiiicate :iii electric .shock to the pcr.sou 

 who.se llcsh it touches. The late Major-! icneriil 

 Davis, of the lloyal Artillery, well known as a 

 most accurate observer of Nature, and an inde- 

 fatigable collectoi- of her treasures, as well :is a 

 most admirable painter of them, once informed 

 me that, when abroad, htiviug taken up this 

 animal and placed it upon his hand, it gave him 

 a considerable shock, as if from an electric jar, 

 with its legs, which he felt as high as his shoul- 

 der; and dropping the creature, be observed 

 six marks upon his hand where the six feet 

 had sU>o{\.—From Kirby and Spence's •^Intro- 

 duction." 



# ♦ • 



Ukmkdy i-oit Onion-wou.m.— Two of our ex- 

 changes have asked for a remedy for this pest. 

 Boiling water is the thing. 



