
 
        
         
		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 unnecessary; 
   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  Schweigger« 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 discordant  
 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.  He 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 th^Batrachia.  The Testudinata  are  here  re- 
 *  Schweigger was assassinated by his guide during a journey in the interior of Sicijy,  - 
 t   Neue Classification der Reptilicn, nach ihren NatUrlichen veriuantltschaflcn, S,-c.  von L. I. Fitzinger: Wien, 1826. 
 duced to the rank of a Tribe,  and  are divided  into  five  families,  which  were  
 adopted, though with considerable improvements, by Mr. Gray.  This arrangement  
 differs but little from the quinary distribution which I proposed at nearly  
 the same period*, ¡and without any knowledge of the existence of such a work  
 as Fitzinger sr  The differences which exist between the method of this author  
 and that which  I proposed,  are almost  all in favour of the former; and I have  
 adopted the general plan, with the improvements of Mr.  Gray,  and some subsequent  
 modifications of my own, in the present work. 
 In 1830 a work, purporting to present “ aN atural System of the Amphibia +,”  
 made its appearance; from the pen of Dr. Wagler.  The unnecessary and unnatural  
 multiplication of genera,  founded upon  very trifling distinctions, into  
 which this author has divided  the Testudinata, appears to me to evince a very  
 inadequate appreciation of the true importance of characters, and is remarkably  
 contrasted with  an  error of the opposite kind in some other parts of his work;  
 whilst the quotations from other authors  are  in  some  cases so incorrect as  to  
 convey  an  exactly -opposite  impression  to  that  originally  intended  The  
 Plates which  illustrate  the  work,  and  of which  one  fasciculus  only  has  yet  
 appeared,  comprising  the Testudinata,  are  beautifully executed,  and  exhibit  
 not only the external form, but the anatomical characters also, of each genus. 
 Passing over thosC casual additions to our information, which have now and  
 then appeared in the description of new species, or the occasional establishment  
 of a genus; I proceed, with mingled  pleasure  and  reluctance;  to  make a  few  
 observations on a portion of the “ Synopsis Reptilium ” of Mr.  Gray, first published  
 as an Appendix to Griffiths’s translation of Cuvier’s “ Regne Animal,” and  
 subsequently,  with considerable alterations,  as a distinct  work§.  As  my object  
 at present  is  not so much  to give  a  critical  examination of  the  different  
 authors to whom I may have-occasion to allude,  as  to  point out to whom we  
 are  most indebted  for  the  gradual  improvement  of  our  knowledge  in  this 
 *  This had remained unpublished for a considerable period, and at length appeared in the Zoological Journal, vol. iii, p. 513, 
 f   Natürliches System der Amphibien ¿yc.  von Dr. Joh. Wagler: München &c. 1830. 
 t   ®ee particularly the characters of my genera Kinixys and Pyxis.  The essential character of the former, as given in the Linn«an  
 Transactions, is, “ Z>ora pars posterior mobilis.”  Dr. Wagler gives it, “ Thoracis pars antica mobilis.”  This is in fact the character of  
 Pyxis, of which this author says, “ Thoracis pars postica mobilis." 
 §  Synopsis Reptilium 5  or Short Descriptions of the Species of Reptiles: by John Edward Gray, &c. Part 1 .1831.