X 
INTRODUCTION. 
were ignorant of that excellent paper. The original intention of this naturalist 
was to produce a full and complete Monograph of the order, illustrated by 
plates. To this undertaking he was led by its having been proposed by the 
French Institute in 1809 ; but being prevented, at that time, from fulfilling this 
intention on the extensive plan at first proposed, he published his Prodromus 
in 1812, though without abandoning his original object, the accomplishment 
of which his untimely death* has now unhappily rendered hopeless. Had 
that project been carried into effect, the present work would have been unne¬ 
cessary ; and it is matter of great regret that so correct a hand as that of 
Schweigger had not completed the task, the outline of which he had so well 
sketched. This tract, from its having appeared in a work comparatively little 
consulted by naturalists in general, has escaped the notice of several subsequent 
writers. Merrem in particular, whose synonyms are so numerous as to prove 
that he has examined almost every previous work on the subject, was wholly 
ignorant of that of Schweigger, the publication of which had preceded his own 
by several years. 
Notwithstanding that the excellence of Schweiggers work consists, in a 
great degree, in its clearness and precision with regard to the identification of 
species, and that in many instances the difficulties arising from the different 
appearances of the same species at different ages are cleared up, and the dis¬ 
cordant synonyms of former authors corrected,—yet when it is considered that 
the information which he possessed of actual specimens, went but little further 
than the collection of the Paris Museum, it will not appear wonderful that 
even these objects should have been but imperfectly fulfilled. Fie enumerates 
seventy-eight species, from which more than thirty must be deducted, either as 
varieties, or as repetitions of the same species, described under different names 
and copied erroneously from other authors. 
A new classification of Reptilia by Fitzinger •f’, appeared in 1826, in which 
the class is divided into two orders : the first, termed Monopnoa , includes all 
those which respire air during the whole of life,—the Reptilia of Merrem; 
the second, Dipnoa , consists of the Batrachia . The Testudinata are here re- 
* Schweigger was assassinated by his guide during a journey in the interior of Sicily. 
t Neue Classification der Reptilien, nach ihren Natilrlichen venvandtschqften, fyc. von L. I. Fitzinger : Wien, 1826, 
