The originality of this volume is to reveal to the reader the fascination of some unfamiliar sensory organs that are sometimes ignored and often misunderstood. These receptors have only recently been identified and their functional specificity is in some cases still a matter for discussion. The four classes of sensory organs considered here differ widely from one another in many respects. One might even say that the only thing they have in common is that they belong to cold-blooded vertebrates. These classes are: 1. the directionally sensitive lateral-line mechanoreceptors of fishes and amphi bians (Chapter 7); 2. the pseudobranchial organs of some teleosts, equipped with pressoreceptors and at least three other types of receptors (osmo- and chemoreceptors) (Chapter 8); 3. the infrared-sensitive pit organs of some snake families (Chapter 9) ; 4. the various kinds of electroreceptors found in several marine and freshwater fish families (Chapters 2 to 6). The first three classes of receptors mentioned above thus rate only one chapter each, whereas five chapters are devoted to the electroreceptors. Electroreception has aroused enormous interest among physiologists in specialties ranging from molecular biology to animal behavior. The resulting quantity of research and discussion fully justifies this disproportion. However, it cannot be denied that the contents of the volume must appear unbalanced and heterogeneous, yet it should not be perceived as a mere juxtaposition of particular and unrelated cases.

The originality of this volume is to reveal to the reader the fascination of some unfamiliar sensory organs that are sometimes ignored and often misunderstood. These receptors have only recently been identified and their functional specificity is in some cases still a matter for discussion. The four classes of sensory organs considered here differ widely from one another in many respects. One might even say that the only thing they have in common is that they belong to cold-blooded vertebrates. These classes are: 1. the directionally sensitive lateral-line mechanoreceptors of fishes and amphi bians (Chapter 7); 2. the pseudobranchial organs of some teleosts, equipped with pressoreceptors and at least three other types of receptors (osmo- and chemoreceptors) (Chapter 8); 3. the infrared-sensitive pit organs of some snake families (Chapter 9) ; 4. the various kinds of electroreceptors found in several marine and freshwater fish families (Chapters 2 to 6). The first three classes of receptors mentioned above thus rate only one chapter each, whereas five chapters are devoted to the electroreceptors. Electroreception has aroused enormous interest among physiologists in specialties ranging from molecular biology to animal behavior. The resulting quantity of research and discussion fully justifies this disproportion. However, it cannot be denied that the contents of the volume must appear unbalanced and heterogeneous, yet it should not be perceived as a mere juxtaposition of particular and unrelated cases.

The originality of this volume is to reveal to the reader the fascination of some unfamiliar sensory organs that are sometimes ignored and often misunderstood. These receptors have only recently been identified and their functional specificity is in some cases still a matter for discussion. The four classes of sensory organs considered here differ widely from one another in many respects. One might even say that the only thing they have in common is that they belong to cold-blooded vertebrates. These classes are: 1. the directionally sensitive lateral-line mechanoreceptors of fishes and amphi bians (Chapter 7); 2. the pseudobranchial organs of some teleosts, equipped with pressoreceptors and at least three other types of receptors (osmo- and chemoreceptors) (Chapter 8); 3. the infrared-sensitive pit organs of some snake families (Chapter 9) ; 4. the various kinds of electroreceptors found in several marine and freshwater fish families (Chapters 2 to 6). The first three classes of receptors mentioned above thus rate only one chapter each, whereas five chapters are devoted to the electroreceptors. Electroreception has aroused enormous interest among physiologists in specialties ranging from molecular biology to animal behavior. The resulting quantity of research and discussion fully justifies this disproportion. However, it cannot be denied that the contents of the volume must appear unbalanced and heterogeneous, yet it should not be perceived as a mere juxtaposition of particular and unrelated cases.

Advances in Physiological Sciences, Volume 31: Sensory Physiology of Aquatic Lower Vertebrates covers the proceedings of the symposia of the 28th International Congress of Physiology. The book presents 17 papers that detail advance findings in the sensory physiology of aquatic lower vertebrates. The coverage of the text includes electroreceptors in Indian catfish teleosts; electroreceptive microampulla in the African mudfish Clarias lazera; and species specificity of electric organ discharges in a sympatric group of gymnotoid fish from Manaus. The book also presents comparative studies, such as the sex differences in the electric organ discharge of Eigenmannia virescens and the effect of gonadal maturation; and behavioral studies, such as social behavior in mormyrid fish. The book will be of great interest to marine biologists, ethologists, and zoologists.

This book evolved through the efforts of several organizations and the dedication of many individuals. In 1987, we received arequest to propose a workshop topic for the Fifth International Theriological Congress (ITC) to be held in August 1989 in Rome, Italy. After looking up the meaning of the word "theriological" in the dictionary and discovering that it pertains to mammalian behavior, we decided a symposium on sensory abilities of whales and dOlphins would be an interesting topic. The ITC convenes only every five years and has the distinction of being very weIl attended by scientists from around the world. We thought that hosting a workshop in conjunction with the ITC would attract a variety of international scientists that rarely have the opportunity to interact. Fortunately for all involved, our prediction was correct. The first two days of the workshop, 23-24 August 1989, were held in conjunction with ITC and the nearly 1,000 attending scientists were able to view our posters and listen to lectures. The third day was limited to only ab out 65 invited scientists who were divided into topical working groups chaired by a rapporteur.

Vestibular physiology has acquired new interest in the past few years. The development of fast aircraft, beginning during the Second World War and continuing through modern supersonic jets and space travel, has increased dramatically the acceleration range to which man is subjected, from prolonged weightlessness to several gs. The labyrinth measures all kinds of acceleration, including gravity. and therefore has taken on particular impor tance in the study of human health in the Space Age. It is understandable. then, that NASA sponsored the Symposium on Vestibular Function and Morphology. a satellite of the Eighth Annual Meeting of the Society of Neuroscience. held October 30-November 1. 1978, at the University of Pittsburgh, which also supported the symposium. The present volume was developed from papers originally presented there. My strategy in editing this book has been to focus upon the vestibular end organ and its direct connections. both peripheral and central, in order to as sure a coherent discussion of the basics of vestibular function, structure, and ultrastructure. Fortunately, it was possible to secure the contributions of a number of outstanding investigators from both the United States and abroad, including functionally oriented morphologists. ultrastructuralists, biophysicists, and vestibular physiologists. The result is a comprehensive discussion of the main mechanisms of the labyrinth: the transduction pro cess at the receptor level, in the semicircular canals, and in the utricular and saccular maculae; the information transfer through neuronal pathways to the nuclei and the cerebellum; and the general organization of the system.