A NEW METAZOAN FROM THE MIDDLE CAMBRIAN OF UTAH AND THE NATURE OF THE VETULICOLIA

Abstract:  A new metazoan, Skeemella clavula gen. et sp. nov., is described from the Middle Cambrian Pierson Cove Formation of the Drum Mountains, Utah, USA. Skeemella is similar to vetulicolians, but differs from other examples of this group in the relative proportions of the anterior and posterior sections, the large number of divisions, and the elongate bifid termination. The posterior section is arthropodan in character. The similarity of this fossil to vetulicolians throws hypotheses of their deuterostome affinity into question and highlights their problematic status.     

Neustonic Marine Craspedomonadales (Choanofiagellates) from Washington and California

SYNOPSIS. Neustonic choanoflagellates can be found in marine tide pools in the San Juan Islands, Washington, and on the Monterey Peninsula, California. Several marine photo-synthetic Chrysophyceae (in the Pedinellaceae), which also occur in these regions, have a basic structure so similar to choanoflagellates that this family is placed in the Craspedomonadales. In pointing out this relationship, the derivation of the Craspedomonadales from pigmented Chrysophyceae is strongly indicated.
In addition to the naked choanoflagellates, which are placed in the Codonosigaceae, these organisms produce loricae of two different types: 1) loricae possibly of cellulose and without visible structure in the light microscope (Salpingoecaceae), 2) loricae composed of silica strands, sometimes forming a mesh with large open spaces (Acanthoecaceae). Members of the latter family seem to be confined to a marine environment and are a prominent part of this investigation. Examination of several species with the electron microscope has revealed interesting details of lorica morphology that are not visible with the light microscope.
Several new combinations of taxa are proposed in addition to new taxa, including 4 new species of Salpingoeca , 3 new species of Diploeca and 4 new species of Pleurasiga. Three new genera are described, Ellisiella gen. nov., Acanthoecopsis gen. nov., and Sportelloeca gen. nov.     

Cadmium Influence on Respiratory Gas Exchange of Pinus resinosa Pollen

Release of CO₂ and uptake of O₂ by Pinus resinosa Ait. pollen treated with 0, 0.004, 0.045, or 0.450 mM Cd²⁺ were determined manometrically. Respiration after 1.5 h was stimulated in the 0.450 mM treatment, but declined sharply after 3.5 h. CO₂ evolution was inhibited more than O₂ uptake. Pretreatment with Cd²⁺ inhibited aflization of exogenous sucrose, and conversely, exogenous sucrose did not overcome Cd²⁺ effects on gas exchange. Cd²⁺ did not act as a classical uncoupler of oxidative phosphorylation. There was no correlation of pollen germination and germ tube elongation with Cd²⁺ effects on gas exchange.