New data on the enigmatic Ocruranus–Eohalobia group of Early Cambrian small skeletal fossils

Abstract: The Ocruranus–Eohalobia group, whose members were variously considered to be brachiopods, bivalves, chitons, tommotiids and coeloscleritophorans, are difficult to classify because of lack of morphological detail and evidence for skeletal reconstruction. New specimens from South China reveal more information about Ocruranus–Eohalobia and allow progress towards deciphering the skeletal reconstruction and phylogenetic affinity of this enigmatic group. Many specimens have a phosphatic inner and outer coat (mould) with empty space in between that resulted from dissolution of the original shell. Moreover, many of the internal moulds show a previously unknown type of shell microstructure that consisted of stacked layers of highly organized, acicular crystallites that radiated from the apex of the shell towards the aperture. The dissolved shell and needle‐like crystals suggest an original calcareous, probably aragonitic, shell mineralogy. A few specimens also show a polygonal texture in regions that suggests the shell had a thin, prismatic inner shell microstructure. Ocruranus and Eohalobia belong to the same skeleton, and we herein synonymize Eohalobia with the older Ocruranus. Moreover, new specimens from Meishucun reveal a third type of shell plate, similar in form and inferred placement to intermediate valves of chitons. Ocruranus is likely a mollusc, and possibly a member of the chiton stem lineage. If so, then the beginning of the known record of chitons would be extended back from late Cambrian (Saukia Zone; Furongian) to early Cambrian (Meishucunian; Series 1).     

A comparison of direct and indirect methods for measuring leaf and surface areas of individual bushes

Indirect estimates of leaf area from measurements with three commercially available instruments (DEMON, LAI-2000 and Sunfleck Ceptometer) were compared with directly measured areas of individual Retama sphaerocarpa bushes. The three indirect methods gave good estimates of the total surface area of individual bushes. For the DEMON, the method of log-linear averaging of transmitted radiation gave estimates closer to directly measured surface area than the method of averaging transmission linearly. For the LAI-2000, estimated surface area index multiplied by canopy projected area gave the best agreement with directly measured values. For measurements with the Sunfleck Ceptometer, values of surface area estimated from the transmission of photosynthetic quantum flux density, without correcting for diffuse radiation, gave the best agreement with directly measured values. Surface areas estimated by the three instruments were not significantly different from directly measured total (leaf + branch + stem) surface areas. Leaf surface area could be calculated from estimated total surface area minus directly measured branch surface area. Measured branch surface area was linearly related to canopy projected area.     

Morphological and Anatomical Studies of Linaria species from South-west Spain: Fruits

A morphological and anatomical study of fruits of 24 taxa ofLinaria Miller from south-west Spain has been made. Followingexamination of these species, by scanning electron and lightmicroscopy, five morphological types are established relatingto hair types, symmetry and dehiscence of capsules. A key tothe different species or groups of species is provided. Finally,dehiscence mechanisms are discussed briefly. Copyright 1999Annals of Botany Company Pericarp, hairs, dehiscence, SEM, Antirrhineae.     

Characterization of Seed Protein Fractions from Castanea spp

Seed proteins of Castanea sativa and C. crenata were extractedby sequential procedures. Albumins accounted for over 20% ofthe total protein. Globulins were the main storage proteinsand represented close to half of the total protein. Additionof 2-mercaptoethanol was essential for maximum extraction ofthe globulins, a fraction with an amino acid composition similarto that of the 1 IS storage protein from legumes. Negligibleamounts of prolamins (<3%) were present in the seeds. Glutelinsrepresented just under 30% of the total protein. The proteinfractions were characterized by electrophoresis in polyacrylamidegels. The glutelin fraction contained unextracted globulinseven when 2-mercaptoethanol was used. Key words: Castanea spp, seeds, storage protein