Distribution, Dispersion, and Behavioral Ecology of the Land Snail Oxyloma retusa (Succineidae)

Oxyloma retusa is a land snail found only along moist margins of freshwater wetlands and lakes. This study quantifies the dispersal pattern of O. retusa along permanent and temporary wetlands and considers the environmental factors to which this snail responds. On a lake shore, snail density peaked in the second or third meter from the water\u27s edge but snails were present in decreasing numbers up to 7 meters inland. In field experiments, marked snails, initially distributed evenly along a shore transect, assumed a similar dispersion pattern within 72 hours. Two color morphs had overlapping but zonal dispersions, the amber morph farther inland than the dark. In drying ponds, snails followed the retreating shoreline. In reflooding of such ponds snails responded by crawling with the water\u27s leading edge or ascending emergent vegetation. It is clear that O. retusa actively selects a precise microhabitat. This habitat selection appears dependent on a combination of physical and biotic factors acting separately and in combination

Land Snails (Pleistocene-Recent) of the Loess Hills: A Preliminary Survey

The Loess Hills and Missouri Alluvial Plain landform regions of western Iowa were surveyed for molluscs in July and August, 1982. We focused on the modern fauna and that of the late Woodfordian (Wisconsinan) Peoria Loess, but a few localities with older and younger Pleistocene and Holocene faunas were also collected. Systematic bulk samples were taken at 95 localities: faunal lists for 75 are included herein. The modern land snail fauna comprises 40 species, most of which are small, drought-resistant cosmopolitan or Interior Province forms. One, or possibly two, Rocky Mountain forms survive as relicts. The modern fauna is depauperate in comparison to that of eastern Iowa. No definite endemic taxa were noted, but several succineid taxa require further study. The Peoria Loess fauna is more diverse and heterogeneous than the extant in its affinities. The total (47 species) includes major Interior Rocky Mountain, Northern, and Midwest Biome components as well as widespread taxa. The Interior element has many more deciduous forest taxa than currently survive. The poorly-known Holocene fauna (34 species) comprises mostly cosmopolitan and Interior taxa, with a few Rocky Mountain or extinct holdovers. In the Loess Hills region, diversity increases pronouncedly from north to south for both Peoria Loess and modern faunas. No clear trend is evident for the Missouri Alluvial Plain. Peoria Loess faunas are most diverse within a mile of the west bluff edge: diversity declines rapidly at more interior easterly sites

Depositional Environment Of The Type Section Of The Seward Formation (Lower Pleistocene), Nebraska

The Seward Formation as originally described was known largely from subsurface data; the authors considered it a fine-grained facies of the Ogallala. It was later correlated with the Elk Creek Till of the Nebraskan glaciation and an outcrop selected in northeastern Seward County as a type section of the unit. Recent research has demonstrated that the Elk Creek Till is much older than the classical Nebraskan tills. The upper part of the exposure designated the type section of the Seward Formation is a massive silt unit that has a thick chernozemic paleosol, and the lower part is laminated silt and clay with a thinner CaCO3-rich paleosol. Land snails collected from a sparsely fossiliferous zone near the base of the massive silt unit represent only five species; 88% are about equally divided between Pupilla muscorum and Gastrocopta armifera, both long lived and widely distributed taxa that indicate open grassland. This faunule and the massive, nearly uniform nature of the silt from which it was collected suggest that part of the sediment may have been deposited as loess. Its thick soil profile, which is buried beneath a laminated silt and fine sand that is overlain by Cedar Bluffs Till a short distance away, is well developed. Judged by post-Wisconsinan soil profile development, it probably would have required several times as long to form. The upper part of the Seward Formation at its type section probably correlates with the Elk Creek Till, which was deposited by the earliest ice to reach the area of eastern Nebraska. The basal part of the formation probably is Pliocene. It is likely that not all the silts identified as Seward Formation from well logs and samples have the same origin as these beds at the outcrop of the type section

Terrestrial snails (Gastropoda: Pulmonata) from Writing-on-Stone Provincial Park, Alberta, Canada

There are few studies on the terrestrial molluscs of the Great Plains of Alberta. Nearly all previously published surveys have focused on the faunas of the Rocky Mountain Foothills, the Cypress Hills, the Parklands of Central Alberta, or the boreal forests. By means of hand-picking and litter samples, we surveyed for the first time the terrestrial snail fauna in the Writing-on-Stone Provincial Park, southern Alberta, Canada. From among the hoodoos (weathered rock formations) and along the cliffs on the north side of the Milk River, we found terrestrial snails at four of our five sites within the hot, dry valley of the river. Our study confirms our assumptions that the terrestrial snail fauna in these hostile habitats lacks diversity

Binder 210, Life histories I-M [Trematoda Taxon Notebooks]

Abstract Binder 210, Life histories I-M [Trematoda Taxon Notebooks]. Harold W. Manter Laboratory of Parasitology, University of Nebraska State Museum, University of Nebraska-Lincoln, Lincoln, Nebraska, USA. Created between 1960 and 1990