ENTOMOLOGIST AND BOTANIST. 



335 



North AmiTicii, of very nuineroua ilisliuot siitcics of Ceei- 

 domijla, ()1 Sciara, of Ceralopoijon, of Ncmatut, and of 

 Brachinus. 

 Upon tlH- siiiue principle I strongly incline to believe that 



the 17-v.':ir r..riii i.r ih>- I'criodii'al Ciraila (C. teptemdccim, 



Linn ) i~ I 'ii^ I -• ii- iv-'iii 111.' i :-y.Hr fomi (C. tre- 



dtciii 



•fori 



closesl . 1 i'i\- imiii'i-i. -|M riinens, to detect 



any Bpec./n: .hik-,LMce buluicu tl.c»c u, u li,rms.» It is very 

 true tliat the 13-year form is conliaeU to liie more southerly 

 rcsious of the United States, while the 17-year form is 

 generally, but not universally, peculiar to (he Northern 

 States; whence it has been, with soni' ii'i-A nf [.1, ;i iliility, 

 inferredthat the 13-year form is noil I, i, I . .nlbrm 



accelerated in its metamorphosis i i a hot 



southern climate. But as these i w i. 1. and 



overlap each other in various local it i' i ill;, 



happens that particiUar broods of tiM ' ii 



the same year, we should certaiiil;, , i '. 



forms belonged to the same species, ih, y v, uul 1 i. .i :■ juii;., 

 intercross, whence would arise an iutermeiliatc variety hav- 

 ing a periodic time of 14, 15 or l(i years . As this does not 

 appear to have taken place, but, on the contrary, there is a 

 pretty sharp dividing line between the habits of the two 

 forms, without any intermediate gi-ades of any consequence, 

 I infer that the iutcrnal organization of the two forms must 

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

 they are exactly alike. Otherwise, what possible reason 

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

 gi'ound in the larva state for nearly 17 years in one county, 

 and in the next adjoining county to lie imdergrouud in the 

 larva state for scarcely 13 years ? 1 presume that even the 

 most bigoted believer in the old theory of species would 

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

 two apparently identical forms are always structurally dis- 

 tinct, whether in their external or in their intci'iial organiza- 

 tion, they must necessarily be distinct species. 



11- be. 



On the other 



uly believe that many perfectly 



' iIiiLi I I -t 'I rurrent, or Which 



ii ries. WeUnda 

 iii.,r|,!i. II, I \ nii>.s, Q. acUulalrJ, 



even now pass ,i; i. - 



dimorphous Inim 



goodexanipleoltli;, ill I'll iiiiii..r|,!i..ii, 

 O. S., which has betu alnaily Ireaf. d of al .^Tiai hiiuln 

 Weflnd another good example of the same thin,' in ( ii i/j 

 Caesinii J 9, Fisher, which is sufficiently di.-iiin.i ir.iui Pi. 

 Periodical Cicada to have been classified as a distiuei ^^n rj.,,, 

 and yet never occurs except in the same year and in the same 

 locality as this last, and what is more extraordinary still , is 

 foimd not only along with the 17-year fornnC. septemdecim) , 

 but also along with the 13-year form'^fc. Iredecim) . Now, if 



""Catsinii were a distinct speoijg, and not, as 1 believe it to be, 

 a mere dimorphous form of U^ seplemdecim and"^. Iredecim, 

 the chances are more tlian a million millions to oue against 

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

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

 appearance. 



It has been ur^ed in opposition to the above view, by au 

 entomological friend of great scientific eminence, that di- 

 morphous forms only appear in one sex. I believe that they 

 veiy frequently appear in both sexes; but of course, in the 

 majority of instances, they are then very naturally accepted 

 as distinct species Suppose, for example, that there AVere 

 such a thing as a cf as well as a g Fapilio Glaucus, Linn., 

 who would then ever have dreamt that Glaucus was a mere 

 dunorphous foi*m of Tumuil It was itrecisely the absence 



-of tlie .f form corresponding to Q Glaucus, that first led 

 entomologists to doubt the possibility of Glaucus being a true 

 bona fide species; and it was uijon similar grounds that Mr 

 Wallace established the existence of several such dimorphous 

 and trimorphous I'apilios in the Malay Archipelago. But 



in point of fact there do really exist, ami 



known to exist, many dimorphous form v^lii li :m "U- 



fined to a single sex. It is only ueci " - . 1 . 1,1 .,, as 

 good illustrations of such a state of thini ■. 1 ■ '.m-.d 



and short-winged forms common to 1 .in 1 ■■• mi'y 



Orlhopterous, Heteropterous and'IIoiiiopteruus ginya, such 

 as Grtjltotalpa, NemoMus, Cynips (.Terasl, Pezomachus, 

 Clioreivs, Hijdrometra , Oerris, Vdia , Prostemmti, Pi/rrhncaris, 



I'aper by Mr, Riley, 



) bearing 11 



:'^;s^' 



on the other hand many foi-ms, which are in reality merely 

 dimori>hous types of one and the same species, are pro- 

 nounced by him to be distinct sjieti'-.s. 



Of course, if we choose to :i ' n il.ji n i 1 \' m ; 



possibly bcdistinctunlesstlu'} .'i ■'■ ■ >'< 



in the imago, and that all In! 1 , '1 n ii 



guishable in the imago are di,l im 1 ^'i - n ,, : ■ 1 n , 



that has been said above will go for nothing, ainl ili.' w ii" 

 doctrine of dimorphous forms, and also, I niiL;lii mlil, 1 

 secondary sexual distinctions, falls to the groinnl. I'.iit 

 luckily for the interests of truth— assumptions are iiol iiiool,- 

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

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

 considerable number of larks. 



[To be continued.'^ 



An Electrical Insect.— You are wr.l ac- 

 quainted with the history and lu-opertics of the 

 Uaia torpedo and Gymnotus electricus; but I 

 dare aver have no idea that any insect possessc- 

 tlieir extraordinary powers; yet I can assure ., 

 you, upon good authority, that Reduoms serra- <fe\ 

 tus, commonly Icnown in the West Indies by the 

 name of tlie "Wheel-bug," can, like them, 

 communicate an electric shook to the person 

 whose flesh it touches. The late Major-General 

 Davis, of the Royal Artillery, well known as a 

 most accurate observer of Nature, and an inde- 

 fatigable collector of her treasures, as well as a 

 most admirable painter of them, once informed 

 me that, when abroad, having taken np this 

 animal and placed it npon 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, he observed 

 six marks upon his hand where the six feet 

 had stood.— i^'row Kirby and Spence's "Intro- 

 duction." 



Hkmedy for Onion-woi£5i.— Two of our ex- 

 changes have asked for a remedy for tliis pest. 

 Boiling water is the thing. 



