58 LABORATORY DIRECTIONS IN 



are but three orders of living Amphibia, and four orders of Reptilia. 

 Note, in the following exercises, that the characters used to separate 

 orders are less fundamenal than those used to separate classes. 



The Orders of Amphibia 



1. Order CAUDATA. Salamanders, newts, etc. 



Characteristics. 



la. Tailed. See Ambystoma, Diemictylus, Cryptobranchus, Pleth- 

 odon, Desmognathus, and others. 



16. External gills sometimes present throughout life (Siren, Necturus, 

 Proteus), sometimes absent in the adult stage (Ambystoma, Triton, and 

 others). 



2. Order SALIENTIA. Frogs, toads. 



Characteristics. 



2a. Tailless. See Rana, Hyla, Chorophilus, Acris, Bufo. 



26. External gills absent in adult. See the forms listed under 2a. 



3. Order APODA. Coecilians. 



Characteristics. 



3a. Without limbs. See Siphonops. 



36. Eyes concealed. See Siphonops, and compare with any of the 

 Salientia. 



The Orders of Reptilia 



1. Order TESTUDINATA. Turtles. 



Characteristics. 



la. Body encased in a bony capsule composed of dermal plates. 

 Observe any turtle. In a cleaned skeleton note how the shell is attached 

 to the skeleton. 



16. Jaws without teeth. Examine a cleaned turtle skull. 



Ic. Quadrate bone immovable. Examine skull. The quadrate is 

 at the angle of the upper jaw, and forms the articular surface for the 

 attachment of the lower jaw. 



Id. Usually five digits in each fore foot, and four or five in each 

 hind foot. Verify in as many specimens as possible. 



le. Only one nasal aperture in skull. Observe in any cleaned skull. 



2. Order RHYNCHOCEPHALIA. This order is represented by only 

 one species, which is found in the New Zealand region. Owing to the 

 rarity of the material, the internal features- listed below cannot be demon- 

 strated. A figure of the whole animal is desirable. 



