ORDER 3  . NUDA OR BATRACII . In this classification we notice three points, which indicate a decided progress towards a natural system . (I) The four orders proposed by Brongniart are no more considered co-subordinate in the class, but the Saurians and Ophidians are associated as sections of the same order, a view held by Aristotle but abandoned by all following naturalists . The distinction between lizards and snakes is carried out in so precise a manner that one genus only, Amphisbaena, is wrongly placed . (2) The true reptiles have now been entirely divested of all heterogeneous elements by relegating positively Caecilia to the Batrachians, a view for which Oppel had been fully prepared by Dumeril, who pointed out in 1807 that " les cecilies se rapprochent considerablement des batraciens auxquels elles semblent her l'ordre entier des serpens." 4 (3) An attempt is made at arranging the genera into families, some of which are still retained at the present day . In thus giving a well-merited prominence to Oppel's labours we are far from wishing to detract from the influence exercised by the master spirit of this period, Cuvier . Without his guidance Oppel probably never would have found a place among the promoters of herpetological science . But Cuvier's principal researches on reptiles were incidental or formed part of some more general plan; Oppel concentrated his on this class only . Cuvier adopts the four orders of reptiles proposed. by Brongniart as equivalent elements of the class, and restores the blind-worms and allied lizards and, what is worse, also the Caecilias, to the Ophidians . The chameleons and geckos are placed in separate groups, and the mode of dividing the latter has been retained to the present day . Also a natural division of the snakes, although the foreign elements mentioned are admitted into the order, is sufficiently indicated by his arrangement of the " vrais serpens proprement dits " as (I) non-venomous snakes, (2) venomous snakes with several maxillary teeth, and (3) venomous snakes with isolated poison-fangs .

He distinguishes the

species of reptiles with a precision not attained in any previous work . Cuvier's researches into the osteology of reptiles had also the object of discovering the means of understanding the fossil remains which now claimed the attention of French, English and German naturalists . Extinct Chelonian and Crocodilian 4 Memoires de zoologie et d'anatomie comparee (Paris, 1807, 8vo);, P . 45 . remains, Pterodactylus, Mosasaurus, Iguanodon, Ichthyosaurus, Teleosaurus, became the subjects of Cuvier's classical treatises, which form the contents of the 5th volume (part 2) of his Recherches sur les ossemens fossiles, oit l'on retablit les caracteres des plusieurs animaux dont les revolutions du globe ont detruit les especes (new ed., Paris, 1824, 4to) . All the succeeding herpetologists adopted either Oppel's or Cuvier's view as to the number of orders of reptiles, or as to stain- the position Batrachians ought to take in their relation vine . to reptiles proper, with the single exception of D .