4 NORTH AMERICAN BATRACIIIA AND KEPTILIA. 



indebted to the Northwestern University, and to the Chicsigo 

 Academy of Sciences, for free access to their museums and 

 libraries. They also feel under especial obligation for assistance 

 of various kinds to Professors S. A. Forbes, 01i\'er Marcy, S. F. 

 Baird, Mr. II. E. Earll, D. S. Jordan, and Doctors J. W. Velie 

 and P. 11. Hoy. In those instances in which the distribution of 

 species has been extended beyond that given in Prof. Cope's 

 check list, the new locality is noted in italics. Preceding the 

 glossary which is appended to the catalogue, will be found a 

 description of the faunal regions of the United States, as limited 

 by Prof. Coj)e. 



SYNOPSIS OF CLASSES. 



Mammary glands absent; blood cold; not less than two 

 aortic arches; no tin rays. 



a. Respiration through whole or part of life eifected by 

 means of branchias; lungs present in adult; two occipital con- 

 dyles; no thoracic diaphragm; usually no scales or scutes, when 

 present they are imbedded in skin; limbs, when present, well 

 developed, with two or more digits; heart trilocular; no sternal 

 ribs; undergo metamorphosis after leaving egg Batrachia . 



h. Respiration never effected by means of branchiiie, but 

 after birth performed by lungs; no separate parasphenoid; a sin- 

 gle convex occipital condyle; sometimes an incomplete thoracic 

 diaphragm; body usually covered with scales or bony plates; 

 metatarsal bones not anchylosed together or with distal tarsal 

 bones; venous and arterial currents of blood mingled either in 

 the heart itself, or at the origin of the aortic arches; undergo no 

 metamorphosis after leaving egg Rejptilia. 



