194 Afr. Gta}f on the Genera of Reptiles^ [SEPt. 



tiles and amphibia, or of the scaly and naked-skinned groups, as 

 they are allowed to be perfectly distinct l)y all modern naturalists, 

 although they do not agree with regard to the rank of the latter 

 group. I ara inclined to follow the opinion of Macleay, Blain- 

 ville, and others, in considering them both as classes, and con* 

 sequently of equal rank. 



Class III.— Rettilia. 



Body covered with scales or hard plates imbedded in the skin ; 

 heart with two auricles and one ventricle respiring by lungs. 

 The blood is cold ; the windpipe ringed ; the ribs are perfect, 

 jind there are several vertebr» ; the penis is distinct, sometimes 

 double. The e^g is covered with a shell, mostly hatched in the 

 body of the mother. 



Synopsis of the Orders. 



Bodi/ covered with imbedded hard plates; legs distinct. 



Ears closed with a valve Emydosauri, 



Ears naked, valveless SaurJ. 



Body covered toith scales, or tico large shields. 



Legs 2-4 weak ; ears naked SacRophidii. 



LegsO; earsO Ophidii. 



Legs 4 ; body covered with two shields. . . Chelonii, 



Mr, Macleay, in his excellent Horcd Entomologies, has 

 observed that the order of this class appears to assume a circu- 

 lar disposition ; the most visible break m this arrangement is in 

 the passage between the snakes and the tortoises ; for the con- 

 nexion between the latter order and the crocodiles must be visi- 

 ble to every one, if they only consult Shaw's figure of the 

 Testudo serpentina, and compare it with that of the crocodile, for 

 it is in fact a crocodile with a shortened body, covered with 

 united instead of distinct shields, and a bird's beak. The pas- 

 sage from the crocodiles to the lizards by means oiihQMinitors, 

 has long been known to naturalists, who have often considered 

 the latter as species of the former genus ; and even Linnaeus 

 placed them in the same section of his genus Lacerta. The 

 Sines have always been placed in the same genus or group with 

 the lizards ; but their affinity with the slow-worms did not escape 

 the penetrating eye of Linnaeus, who observes that the Lacerta 

 Chalcides, is " Media inter Lacertas et Angues;" and the union 

 of the genera Sincus, Anguis, and Amphisbena, into an order, 

 although it has not been done by any zoologist that I am 

 aware of, appears to be strictly natural, for the feet in this order 

 exist in such various degrees of developement, that the 

 being with or without them appears to be only a family 

 or generic character, and not ordinal. Linnaeus placed the 

 genera Tortrix and Eryx of the true serpents as species of his 



