prr.Lic'ATioxs of charles gieard, m. d. 6 



1851. UiiiAiiK, Ciiahlks— ( '(Mitimird. 



IMiijenia maculala, (jrd 3 



Vicinities of I'liila., Lciily, Giranl. 



ProHouia xiargiuatnm, Lcidy 3 



VitiiiititH of I'liilii., Lcidy. 



Planocera elliptica, ( i rd 3 



Polycelix variabiliii, (ird . . . . .^ 3 



ProsthiostoinuiH ijrac!li% Clrd 3 



PKOcERonES, (iirard 4 



Procerodes Wheatlandi, (ird -. 4 



Vortex 'Warreni, Grd 4 



Vortex Candida, rd 4 



Monoeelis ipatuUcauda, ii. s 4 



Bonton llarbor, Cli. Girard. 



Nemerteans. 



Ptlia qracilin, ii . s 4 



BoHtoii Harl)or, ("li. (iirard. 

 TetraiteiiDiia nerpeiitina, ii. s 4 



Boston Harbor, Cli.Oirard. 

 Meckelia fragilU, ii. s 4 



Chelsea Beach (Mass.), Ch. Giravd. 



19. 



1851. GiRARP, Charles. On a new Genus of American C'ottoids. 



Provirdiuffs Ronion Society of Xatiiral ffistorii, iv, 18-lH. 1851. 



Trigi.op.sis, 11. g 19 



Triglopais Thoinpxoni, ii. .s 19 



Oswego, Professor Baird. 



20. 



1851. Girard, Charles. Historical skotcli of Gordiacenn. 



Proceedbujs Acndeuiy of Xatiiml Sciences rhiUideJphiu, v, 279-284. 1851. 

 Observations on the anatomical structure of Gordiace;¥. 



21. 



1851. Girard, Charles. The Seventeen-year Locusts {Cicada septeudecim.) 

 liosion Evcniutj Traveller, Sept. 3, 1851. 



The metamorphosis of the 17-year locust have been so thoroughly investigated, especially 

 by the late iliss H. Morris, of Gennantown, Pa., that no roimi is left for any doul)t as to the 

 jieriod of 17 years of its nndergronnd life. 



The phenomenon of its regular appearance above ground every 17 years has attracted the 

 attention of the learned community, which carefully recorded the ))eriods during the present 

 century. A curious stat(Mnent resulteil therefrom, viz, that, although reappearing regularly 

 every 17 years in the same locality, minor swanns of that insect were noticed in other locali 

 ties, apiH'ariiig likewise regularly every 17 years, the ])eriods of which, liowever, were not 

 synchronic « ith those of the appearance of the larger swarms. 



The question then arose whether the insect had been created at repeated times during a 

 given epoch in the history of the earth, or whether they all jiroceeded from a single creation 

 in a single locality, whence they subsequently spread into the manifold places where they 

 are now observed. 



The late Dr. Burnett, of Boston, having brought the matter before the American Associa- 

 tion for the Advancenient of Science at the Albany meeting of August, 1852, upheld the 

 theory of repeated creations of the insect in various localities. 



Dr. Girard took up the opjiosite view, defending the idea of one sole creation on a single 

 locality, imimting the existenct^ of the minor swarms to accidental mig)'ati(Uis and climatic 

 influences, without actual transformation in their anatomical and zoohigical cLaraetera. 



