This paper is based on the marshalling of a wide variety of evidence in an effort to understand the origins and evolutionary deployment of a faunal unit, namely the species of toads of the genus Bujo that occur in North America. Another purpose is to learn the mechanisms of speciation in this group. Toads are typically xericor subxericadapted anurans, and this is reflected in the external morphology. They are typically thick-skinned and often spiny because of the presence of keratinized tubercles. Bony and keratinized ridges (crests) are often present on the head. The inner metatarsal tubercle is sometimes modified into a trenchant digging organ or \"spade.\" Venom-secreting parotoid glands are slightly to highly developed. Toads retain the primitive habit of laying eggs in water. They are typically opportunistic breeders (dependent on adequate rains), although some have become semi-aquatic and independent of rainfall in adaptation to harsh

Evolutionary Relationships of North American Toads of the Genus Bufo: A Progress Report

Bidder's organ is an ovary-like structure, which develops from the anterior part of the gonadal ridge in anuran amphibians belonging to the Bufonidae family. Bidder's organs form in both males and females. Because Bidder's organ contains female germ cells (oocytes), the bufonid males are de facto hermaphrodites. Due to similarity with the undeveloped ovary, Bidder's organ was, in early literature, described, inaccurately, as a structure present only in males. Due to the fact that Bidder's organ is a unique structure present only in Bufonidae, it is not well studied and its function still remains a mystery. Here we describe the development and structure of Bidder's organs, summarize the knowledge on gene expression and steroidogenic activity in these organs, and present hypotheses regarding Bidder's organ function.

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Bidder's organ--structure, development and function.

To one degree or another, most materials experience some type of interaction with a large number of diverse environments. Often, such interactions impair a material’s usefulness as a result of the deterioration of its mechanical properties (e.g., ductility and strength), other physical properties, or appearance. Occasionally, to the chagrin of a design engineer, the degradation behavior of a material for some application is ignored, with adverse consequences. Deteriorative mechanisms are different for the three material types. In metals, there is actual material loss either by dissolution (corrosion) or by the formation of nonmetallic scale or film (oxidation). Ceramic materials are relatively resistant to deterioration, which usually occurs at elevated temperatures or in rather extreme environments; the process is frequently also called corrosion. For polymers, mechanisms and consequences differ from those for metals and ceramics, and the term degradation is most frequently used. Polymers may dissolve when exposed to a liquid solvent, or they may absorb the solvent and swell; also, electromagnetic radiation (primarily ultraviolet) and heat may cause alterations in their molecular structure. Corrosion is defined as the destructive and unintentional attack of a metal; it is electrochemical and ordinarily begins at the surface. The problem of metallic corrosion is one of significant proportions; in economic terms, it has been estimated that approximately 5% of an industrialized nation’s income is spent on corrosion prevention and the maintenance or replacement of products lost or contaminated as a result of corrosion reactions. The consequences of corrosion are all too common. Familiar examples include the rusting of automotive body panels and radiator and exhaust components.

Forms of Corrosion

For many years values of gravity all over the world have been obtained relative to that at Potsdam by observations with invariable pendulums. The value at Potsdam was determined by Kuhnen and Furtwangler (1906) by Kater’s method and a standard error of 0.003 cm./sec.2 was claimed for the result. Any error in the Potsdam value would involve an equal error in the related values all over the world. As the acceleration of gravity is involved in all measurements of force with the balance and thus in the unit of electric current and in such quantities as the velocity of an α -particle, it is important to know whether the accepted value at Potsdam has the accuracy claimed for it. A recent absolute determination by Heyl and Cook (1936) at the National Bureau of Standards, Washington, D.C., gave a result 0.020 cm./sec.2 less than that obtained by comparison with Potsdam, whilst one by Clark at the National Physical Laboratory, Teddington gave 0.0138 cm./sec.2 less. The relative gravity connexion between Potsdam and Washington is strong, but those between Teddington and Washington and between Teddington and Potsdam are weak and indirect. Advantage has therefore been taken of the visit of the authors to Washington to attend the recent meeting of the International Union of Geodesy and Geophysics to make a comparison of the values of g at the places used for the absolute determinations at the National Physical Laboratory and at the National Bureau of Standards. It had been intended also to connect the National Physical Laboratory directly with Potsdam, but the outbreak of war has made it necessary for this to be postponed.

Comparison of the Acceleration due to Gravity at the National Laboratory, Teddington and the Bureau of Standards, Washington, D.C.

An annotated check list of the amphibians and reptiles of Colorado

T HE secondary sexual characters of amphibia have proved of considerable taxonomic importance, and have consequently been studied in considerable detail. The best recent summary of these is probably that of Noble (1931), who gives numerous references. The present paper is a summary of these characters as they have been observed in the common toad of southern Asia, Bufo melanostictus Schneider. Schneider's original description (1799) does not include mention of sexual differences; but one male character, viz., possession of the subgular vocal sac, was noted and recorded as early as 1841 by Dumbril and Bibron under the synonym Bufo scaber Daudin (part). Stejneger (1907) described in detail the external features of the two sexes from preserved specimens collected in Formosa. Only one specimen of each sex was described in detail, however, and it is therefore not unusual that the writer has found that certain of the recorded differences are not constant. My observations are based primarily on the detailed examination of 27 males and 41 females, and examination of certain external characters of 5 additional males, all collected, and examined fresh, at Bangkok, Siam, between October, 1928, and May, 1930. These were the largest individuals from a total collection of over 200. The large series in the American Museum of Natural History has been subsequently studied, through the courtesy of Mr. Clifford H. Pope, who collected most of the specimens. I am indebted to my colleagues in Chulalongkorn University, Bangkok, for much assistance during the course of the studies in Bangkok. The sexual differences are here treated in two groups, qualitative, and quantitative. QUALITATIVE DIFFERENCES BETWEEN THE SEXES BEHAVIOR.-Pressure on the sides of the body, behind the fore-limbs, of all mature males elicited the croak reflex. The croak was a guttural trill, not particularly loud. The same treatment of females was followed usually by considerable swelling of the body, and often by forcible discharge of urine. SUB-GULAR VOCAL SAc.-Males possess a black-pigmented, sub-gular vocal sac, which usually opens into the pharynx by a single, asymmetrically located slit. Of the 13 males examined for this character, 8 had the opening on the right side of the tongue (Fig. la), 4 on the left side, and one had two openings, placed bilaterally (Fig. ib). Dumeril and Bibron (1841) and Stejneger (1907) described specimens with bilateral openings, but made no mention of the apparently more usual unilateral condition. COLOR.-The most consistent external difference between the sexes was found to be the color of the upper throat. Flower (1896) thought the "bright yellow" chin of males was confined to the breeding season.

Gordon Alexander

Papers

Secondary Sexual Characters of Bufo melanostictus Schneider

Bidder's Organ in Bufo melanostictus Schneider

Erythrocyte Counts in Colorado Ambystoma