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Chickens found brown efts unpalatable. They hesitated longer in attacking efts compared with control Desmognathus ochrophaeus, attacked them less frequently, and for a shorter duration. Only one of 50 efts was killed (not eaten), whereas 47 of 50 D. ochrophaeus were eaten. When one red eft and one specimen of Pseudotriton montanus diastictus were offered to each of five chickens that had previous experience with brown efts, time to attack on both was the same as on D. ochrophaeus, showing that the chickens discriminated between these red sala- manders and brown efts. Duration of attack on red efts resembled that on brown efts, but was much longer on P. m. diastictus regardless of which reddish species was offered first. No red eft was killed; all five specimens of P. m. diastictus were killed but only one eaten. Palatability of P. m. diastictus was clearly less than that of D. ochrophaeus. Brown efts seem to be exposed to greater risk of damage by predators than are red efts because their skin toxins are not reinforced by bright skin coloring; in nature, however, this risk may be reduced by defensive posturing that exposes yellow underparts.

Laboratory experiments were conducted using toads, Bufo terrestris, and tree- frogs, Hyla cinerea, as predators and honeybees, Apis mellifera, as models. Bees from which the stinging apparatus had been removed served as mimics. Model and mimic bees were offered randomly with the models at frequencies of 10%, 30%, and 50% to the toads and 10%, 20%, and 50% to the treefrogs. The corresponding percentages of the model-mimic population eaten were 53.6%, 35.3%, and 19.8% (toads) and 29.6%, 17.4%, and 7.0% (treefrogs). The frequencies of bees eaten as a function of percent models in the prey population can be described by the mathematical model of predation presented previously (Huheey, 1964, 1976). Predator memory values (n) of 8.0 (toads) and 28.7 (treefrogs) were obtained. Various factors affecting the behavior of the predator with respect to the value of n are discussed: toxicity vs. distastefulness, alternate prey, and predator strategy. It is concluded that n is better viewed as a risk-taking strategy on the part of the predator than as a simple memory parameter.

its, it has been considered rare, and its range was long thought to be from South Carolina to Louisiana. Recent collecting has brought new specimens to light, and the recorded range has been extended from Virginia to Texas. It is the purpose of this study to delimit the range and explore the regional variation exhibited by this species. It has been found that the specimens fall into three distinct populations which appear to warrant subspecific recognition. A total of 255 specimens was examined, including sizable series from most areas of the range. Alabama, western Georgia, and North Carolina are sparsely represented. The following persons and institutions made specimens or data available (initials in parentheses are those used in subsequent references to these specimens): W. Frank Blair, University of Texas (TNHC); W. E. Brode, Gulf Coast Research Laboratory (GCRL); Bryce C. Brown (BCB), Strecker Museum, Baylor University (SM); E. Milby Burton, Charleston Museum (ChM); Fred R. Cagle, Tulane University (TU); Charles C. Carpenter, University of Oklahoma (UOMZ); Doris M. Cochran, United States National Museum

A divergence factor (D) is defined which indicates the rate of species replacement in a given area. All geographical points having equal values of D may be connected by a contour line (isometabasis). The resulting contour map indicates regions of little change (equivalent to biotic provinces) and regions of rapid change (equivalent to province boundaries). This procedure reduces the possibility of subjective bias in analyzing zoogeographic data. The herptofaunal data from the state of Illinois are used to illustrate the potential advantages of the method.