694 IIERPETOLOGY worm, &o.); 6, cacilia ; 7, ran (frogs and salamanders) ; and 8, ichthyodes (sirens, meno- branchs, &c.), from their fish-like forms. He includes 248 genera. In chronological order would come here the classification of Dumeril and Bibron, whose work, Erpetologie generate, ou histoire naturelle complete des reptiles (10 vols. 8vo, 1835-'50), is the most extensive ever published on this subject ; though more recent observers have introduced some changes, their classification may be considered as representing, on the whole, the actual state of herpetology. When their work was commenced, in 1835, the materials at their command numbered about 850 species, which number they largely in- creased. They divide reptiles into the four A orders of chelonians or tortoises, saurians or lizards, ophidians or serpents, and batrachians or frogs and salamanders. McLeay, in the HOTCB EntomologiccB (1819-'21), divides the ani- mal kingdom into five great circles, each con- taining five smaller ones; the five groups of the class reptiles he considers to stand in the following natural order : 1, the chelonians ; 2, emydosaurians, or crocodiles ; 3, saurians ; 4, dipod or two-footed serpents ; and 5, apod or true serpents the extremities of the column seeming to meet in the chelodina longicollis (Gray), and the whole forming a group distin- guished from birds by being cold-blooded, and from amphibia by having two auricles to the heart, by undergoing no metamorphosis, and by a different method of generation. One great defect of this classification is, that it leaves entirely out of view the fossil enaliosaurian reptiles. Swainson, in his "Natural History of the Monocardian Animals" (Lardner's "Cy- clopaedia," vol. ii., 1839), like McLeay, makes a distinct class of the amphibia, and divides reptiles into five orders : 1, emydosaurians, or crocodiles ; 2, chelonians ; 3, enaliosaurians (ichthyosaurus, &c.) ; 4, ophidians ; and 5, sau- rians. Strauss-Durckheim, in his Traite d'ana- tomie comparative (1843), divides his third class, or reptiles, into the three orders of saurians, ophidians, and batrachians, making a separate and fourth class of the chelonians, with the single order of testudinata. Stannius, in the second volume of the second edition of his " Manual of Comparative Anatomy " (Berlin, 1854-'G), in the class 17, reptilia, makes two subclasses, dipnoa and monopnoa. Milne-Ed- wards, in his Cours elementaire d'histoire natu- relle (1855), divides the vertebrata or osteo- zoaires into two sub-branches ; in 1, the allan- toidia, he places with mammals and birds the class of reptiles, with the orders chelonia, sauria, and ophidia; and in 2, anallantoldia, with fishes, he places the batrachians, with the orders anura, urodela, perennibranchia, and ccBcilicB. There are several German systems of classification, which deserve notice in regard to reptiles. Von Baer, in 1826-'8, in his verte- brate or doubly symmetrical type, rises from osseous fishes to amphibia, in which lungs are formed, the branchial fringes remaining in the sirens and disappearing in the urodela and anura; thence to reptiles, which acquire an allantois, but have no umbilical cord, nor wings, nor air sacs, the last two being characteristic of birds. Van Beneden, in his Anatomie compa- ree (Brussels, about 1855), makes reptiles and batrachians the third and fourth classes in his hypocotyledones or hypovitellians (vertebrata), in which the vitellus enters the body from the ventral side ; the reptiles he divides into cro- codili, chelonii, ophidii, saurii, pterodactyli, si- mosauri, plesiosauri, and ichthyosauri; and the batrachians into labyrinthodontes, peromelia, anura, urodela, and lepidosirenia. Vogt, in his Zoologische Brief e (1851), bases his clas- sification on the contrast between the embryo and the yolk, and makes the reptiles and am- phibians the third and fourth classes in the vertebrata, or animals with the yolk ventral ; in reptiles he includes the orders ophidia, sauria, pterodactylia, hydrosauria, and chelonia ; and in amphibia the orders lepidota, apoda, cau- data, and anura. These classifications are im- portant, as showing the tendency of modern zoology to combine embryological with exter- nal and structural characters, in establishing the natural divisions among animals ; for full details and interesting remarks on these and other systems, the reader is referred to the "Essay on Classification" in Prof. Agassiz's " Contributions to the Natural History of the United States," vol. i. T. Rymer Jones, in the article "Reptilia," in the "Cyclopaedia of Anatomy and Physiology," vol. iv., gives the following classification, considering the batra- chians as a separate class : Order I., chelonia; II., sauria; and III., ophidia. Van der Hoe- ven, in his " Handbook of Zoology " (English translation, 1858), thinks De Blainville went too far in elevating the batrachians into a class, and goes back toward the old fourfold division, adding however two orders. He divides rep- tiles into two sections: diplopnoa or psiloder- ma, breathing by lungs or gills and with smooth skin; and haplopnoa, breathing by lungs only, and with a scaly skin. Owen, in the "Anato- my of Vertebrates " (vol. i., 1866), makes the following subclasses in the reptilian division of the hcematocrya or cold-blooded animals, which include also the fishes : subclass 5, with orders ichthyopterygia, ichthyosaurs ; sauropterygia, plesiosaurs; anomodontia, like dicynodon and rhynchosaurus (all of the above extinct) ; chelonia, tortoises and turtles ; lacertilia, liz- ards, &c. ; ophidia, serpents ; crocodilia ; di- nosauria, iguanodon, &c. ; and pterosauria, pterodactyl, &c. (the last two also extinct). Prof. T. H. Huxley, in the "Introduction to the Classification of Animals " (London, 1869, really dating back to 1864), calls the second "province" of vertebrates sauropsida, com- prising reptiles and birds, the close affinity be- tween the two being shown by such reptilian birds or bird-like reptiles as archc&opteryx. (See AECH^OPTERTX.) The reptiles are the second class of the province, there being four
