Cosomys, a New Genus of Vole from the Pliocene of California

Rodents are of rather common occurrence in the later Tertiary of North America, yet voles have been completely absent from the record with the exception of a single tooth of Neofiber found in the upper Pliocene San Pedro Valley beds of Arizona. Consequently material representing this important group should prove of interest in an interpretation of the history of the voles in North America. The specimens described in this paper are from late Cenozoic mammal-bearing beds exposed on the flanks of the Coso Mountains along the eastern margin of Owens Valley, nine and one-half miles east of Olancha, California. The age of the deposits from which the rodent material comes has been tentatively regarded as upper Pliocene by Dr. Chester Stock of the California Institute of Technology. A determination of age has been afforded chiefly by horse material from the same locality. The author wishes to thank Dr. Stock for the opportunity to study the material and for advice during the course of the investigation. Specimens of Recent voles were loaned for comparison by Mr. Donald R. Dickey of the California Institute of Technology, and by the United States National Museum. Preparation of the illustrations was super- vised by Mr. John L. Ridgway

A new species of Dipoides from the Pliocene of eastern Oregon

Numerous remains of castoroid rodents from the Tertiary of North America have been referred to the Old World genus Dipoides Jaeger. Apparently, most of the material represents types generically distinct from Dipoides, and the genus is actually represented by very few specimens of fragmentary character. It is not the purpose of this paper, however, to present the distinguishing characters which separate the true Dipoides from other American beavers with simplified dental pattern, but to describe remains of a Dipoides species collected by California Institute of Technology field parties in Pliocene beds in the region of Rome, Oregon. R. A. Stirton, of the University of California, has made a study of the taxonomy and relationships of members of the beaver group and his report on the Castoridae is now in press

New middle Pliocene rodent and lagomorph faunas from Oregon and California

The purpose of this paper is the description of two rodent faunas in the collections of the California Institute of Technology. Although coming from widely separated areas, these assemblages are of approximately the same age. The first fauna to be discussed is that from Pliocene strata near Rome, Malheur County, Oregon. It exhibits some diversity of type although the associated larger mammals are known by very fragmentary remains. The second rodent fauna comes from the Kern River deposits, San Joaquin Valley, California. The Kern River rodents and lagomorphs, and the larger mammals found with them, share with other Tertiary assemblages of the San Joaquin Valley the important task of determining the time relationships between the nonmarine deposits in which they are found and the standard marine sections of the Pacific Coast. The illustrations for this paper are from photographs by the late H. Wm. Menke, and have been carefully retouched and arranged into plates by John L. Ridgway

PRICE RISK MANAGEMENT STRATEGIES FOR GRAIN IMPORTERS

The presence of multiple sources of uncertainty complicates hedging decisions. One of these is the output price and its correlation with input prices. The other is how far forward a firm covers its positions. This study analyzes hedging strategies for grain importers as processors. The analytical model addresses questions of the hedge horizon and accounts for the correlation between input and output prices and exchange rate risk. A theoretical model was developed explicitly modeling the operations of a grain importing firm. The concept of strategic demand for hedging was developed in the context of an analytical model, representing the adjustment in hedge ratios in relation to the hedge horizon and input-output price correlations. Results indicated that the hedging demand diminishes as the time horizon increases, that input-output price correlations have an important impact on hedging, as does the exchange rate. The model also illustrated the impact of price controls and/or output contracting on risk exposure and the demand for hedging.price risk uncertainty, hedging, grain, importers, International Relations/Trade, Risk and Uncertainty,

A new species of Dipoides from the Pliocene of eastern Oregon

Numerous remains of castoroid rodents from the Tertiary of North America have been referred to the Old World genus Dipoides Jaeger. Apparently, most of the material represents types generically distinct from Dipoides, and the genus is actually represented by very few specimens of fragmentary character. It is not the purpose of this paper, however, to present the distinguishing characters which separate the true Dipoides from other American beavers with simplified dental pattern, but to describe remains of a Dipoides species collected by California Institute of Technology field parties in Pliocene beds in the region of Rome, Oregon. R. A. Stirton, of the University of California, has made a study of the taxonomy and relationships of members of the beaver group and his report on the Castoridae is now in press

A rodent fauna from later Cenozoic beds of southwestern Idaho

The late Pliocene or early Pleistocene continental deposits occurring in southwestern Idaho have yielded scattered fossil mammalian remains during the past forty years or more. However, with the exception of beaver material described as Castor accessor by O. P. Hay nothing has been recorded concerning the rodents from these beds. That a diversified assemblage of types occurs in these later Cenozoic sediments is clearly shown by collections procured in recent years in the course of palaeontological explorations along the Snake River near Grand View and Hagerman, Idaho. The westerly of the two principal localities in this region of Idaho is situated on the west side of the Snake River approximately thirteen miles northwest of the town of Grand View. This site was investigated by the California Institute of Technology. The Hagerman locality, where extensive excavations were conducted by the United States National Museum, is situated on the Snake River across from the town of Hagerman. In an airline, the distance between the localities at Grand View and Hagerman is approximately sixty miles. The United States National Museum has generously permitted me to borrow the rodent collections obtained by that institution at the Hagerman locality. The beaver remains were not included, since important studies of this group are being conducted elsewhere. The present paper embraces therefore a study of the rodent types now known from the Hagerman and Grand View localities, with the exception of the material noted above, and grateful acknowledgment is made here for opportunity to study the National Museum collections. Recent comparative material was loaned by the Division of Vertebrate Zoology, California Institute. The illustrations of the rodent material were prepared from photographic enlargements by John L. Ridgway. The author also wishes to thank Dr. Chester Stock for opportunity to study the California Institute collections and for supervision of the work, as well as for a critical reading of the manuscript

A new genus of lagomorph from the Pliocene of Mexico

Among mammalian remains recently obtained in Pliocene deposits near Rincon, Chihuahua, Mexico, are materials of a new genus of lagomorph. Lagomorph types other than Hypolagus are rare in the later Tertiary of the New World, and the present record should be of interest to students of fossil leporids