Abstract.-A study of the hearing of the penguin Sphenikcus demersus, in terms of the cochlear potentials, showed sensitivity over a range at least of 100 to 15,000 Hz, with the best sensitivity in the region of 600 to 4000 Hz. The form of the sensitivity function is consistent with the vocalizations of these animals. In general, this species of penguin shows good agreement with other birds in both the form and range of auditory sensitivity.The auditory capabilities of one species of penguin, Spheniscus demermus, commonly called the Blackfooted or Jackass Penguin, were investigated by means of the cochlear potentials. This is one of the smaller penguin species, breeding on islands off the western coast of South Africa. Three animals were used for the observations.The animals were anesthetized with ethyl carbamate, administered intraperitoneally in a 20 per cent solution at a dosage of 0.01 cc per gram of body weight. During the experiments the animal rested on a heating blanket, and a body temperature of 380C was maintained by means of a temperature probe in the cloaca that led to a regulating instrument.The middle ear cavity was exposed by a lateral approach, as indicated in Figure 1. The right side of the head is shown, with the region of the skin incision indicated. The removal of skin and muscle tissue in this region exposed the poster-

To determine what behavioral changes are caused by consumption of Lake Ontario salmon, a 30% diet of Lake Ontario or control Pacific Ocean salmon was fed to rats for 20 days. In Experiments 1 and 2 (preference-for-predictability E-maze test), rats fed Lake Ontario salmon developed a preference for predictable food rewards more quickly than did the control rats. In Experiments 3 (passive avoidance) and 4 (conditioned suppression), rats fed Lake Ontario salmon suppressed responding to food far more after the introduction of mild electric shocks than did control rats. All results supported the hypothesis that ingestion of Lake Ontario salmon, contaminated with polychlorinated biphenyls, mercury, lead, etc., increases the reactivity of rats to aversive events. The results were successfully simulated by DMOD, a mathematical model of learning, using the assumption that rats fed Lake Ontario salmon find unpredictable nonreward and mild shock more aversive.

Optokinetic performance was measured in two groups of red-eared turtles; nex t, one group received bilateral ablation of the general cortex and the other received bilateral ablation of the optic tectum. After recovery, optokinetic performance was measured again. Cortical ablation had no effect, whereas tectal ablation brought about a deficit in responding in a 19stripe, but not in a 4-stripe drum. These results support the traditional view that the optic tectum is a major visual center in reptiles.

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