628 BIOLOGY. 



Viewed in accordance with the perfection of the limbs, 

 the Salamanders and Frogs ought to be regarded as the 

 highest in rank; but their scaleless tegument, their 

 development out of spawn in the water, as well as 

 branchiae brings them near to the Fishes. In other 

 respects their position is determined by the dental for- 

 mula, which, as I ha,ve already shown, belongs to the 

 limbs and thus to the motor system. 



The position of the nostrils is now, throughout the 

 class, in front of and upon the snout, being no longer 

 situated almost on the forehead or vertex, as in Fishes. 

 Their relation to the scales is likewise of importance for 

 the purposes of division. 



The naked Salamanders and Frogs will occupy the 

 lowest place. By their form, absence of teeth, and mode 

 of life, the Chelonia are allied to them. 



Then follow the Serpents and Lizards with a perfect 

 set of teeth. The Serpents are distinguished from the 

 Lizards by their want of feet and the long bifid tongue 

 inclosed within a sheath. 



Among the Lizards apodal species occur, as the Blind- 

 worms ; but they have under the skin some pedal bones, 

 and are, in addition to this, sufficiently distinguished from 

 the Serpents by the short and sheathless tongue. 



Among the Lizards with perfect feet there are some 

 with small visual organs, like as in the Serpents ; others 

 with unusually large eyes, e. g. the Chameleon, Gecko, 

 Ichthyosauri, and Crocodiles. All other Lizards, the 

 Serpents, Chelonia, Salamanders and Frogs, have small 

 eyes and consequently follow each other. 



The Crocodile has teeth articulated by gomphosis, and 

 consequently resembles the Thricozoa. 



I divide the present class therefore into the following 

 groups. 



A. DERMAL REPTILES SMALL-EYED. 



Order 1. Protozooid Eeptuia Kroten. 

 3543. Body slimy and scaleless, or maxilla? devoid of 

 teeth. 



