Abstract
1. Convenient methods of obtaining and preparing the serum antigens of reptiles are described. Antisera are prepared principally by a subcutaneous mode of injection. Precipitin testing is almost exclusively by the quantitative photron-reflecto-meter procedure of Boyden and DeFalco. Ring tests are used to verify the weakest heterologous reactions. 2. Quantitative investigation of the systematic serology of common reptiles corroborated the findings of Graham-Smith. The alligator was serologically closer to the turtle (Chelydra) than to either lizard (Varanus) or snake (Coluber). Quantitative serological comparisons revealed that Lapeinis (sea snake) and Naja (cobra) were closer to each other than to Coluber (racer) or Crotalus (rattlesnake). The pygmy rattlesnake, Sistrurus, was found to be serologically closer to Crotalus ("true" rattlesnake) than to Agkistrodon (moccasin), some of whose morphological features it shares. From serological study of available material, it was suggested that the rattlesnakes are more closely interrelated than are the moccasins. Such information compares favorably with the fact that the moccasins are discontinuously distributed geographically, whereas the rattlesnakes are not.