1851.] 279 



Hislorical SlrtcA of Gordiacea-. 



Bt Charles Girard. 



I. 



There are groups, amongst the invertebrates of the animal kingdom, whose 

 natural history has made but little progress, although known to science for more 

 than half a century. 



The animals of which they are composed being generally of a diminutive size, 

 modest in form, modest in colors, have been looked at with indifference, thought 

 unworthy of a careful investigation, and deemed of too small an importance in a 

 general system of classification. 



Every living being, however, is entitled to occupy a rank in the creation ; 

 every one has its place, its aim, and its design. 



Yet some are called enigmatic, paradoxical, doubtful, as if to the Creator's 

 mind, any thing or any being could be either an enigma, a paradox, or a doubt. 

 Such groups, we must acknowledge, present great difficulties to investigators : 

 but let investigators be patient and laborious, and they will gradually sweep 

 away the enigmas, the paradoxes, and the doubts. 



When the researches on a group are slow, and embrace a long period, then it 

 becomes necessary, for the safe and future advancement of its natural history, to 

 recapitulate all the data in their chronology. These data will become a guide 

 into the various desiderata for new observations. 



Most diverse opinions are still entertained concerning Gordiaceae, and import- 

 ant zoological questions are still waiting the results of further investigations. 



Are Gordiaceae indigenous in America, or introduced from abroad ? If they are 

 indigenous amongst us, are they identical with, or specifically different from, the 

 European species ? 



Here commences a labor of comparison between the internal structure and 

 external appearance of specimens from both countries. Besides, specimens from 

 all the localities of one country should be compared, in order to ascertain the 

 number of species. Their embryology and metamorphosis must be traced; their 

 habits recorded, in order to enable us to assign a natural position to that family 

 in the class of worms. 



If they are introduced on this continent, how, where, and how long since, did 

 that event take place ? What is their geographical distribution and progressive 

 migration to the places where they are now found ? 



Some facts, which we already possess, and which are related hereafter, rather 

 enforce the belief of their aboriginal nature, than that of their introduction. Even 

 in the case of an identity between the Ameriean and European Gordiaceae, these 

 worms still deserve special attention from American anatomists, as the 

 latter might be successful in elucidating the controverted anatomical questions 

 which divide the naturalists of the old world. 



II. 



The genus Gordius was established by O. F. Miiller during the last century.* 

 Under that name were included aquatic worms, others living in moist grounds, 



* Vermium terrestrium et fluviatilium historia, 1773. 



