The jaw apparatus of the regular echinoids is moved by a complex of muscles. Of these the largest and most accessible are the lantern retractor muscles which originate on the auricles and insert upon the pyramids which enclose the teeth. Preliminary experiments using Parechinus angulosus Mortensen showed that, while in this species these muscles could not be stimulated indirectly by way of elec...

Bindin plays a central role in sperm-egg attachment and fusion in sea urchins (echinoids). Previous studies determined the DNA sequence of bindin in two orders of the class Echinoidea, representing 10% of all echinoid species. We report sequences of mature bindin from five additional genera, representing four new orders, including the distantly related sand dollars, heart urchins, and pencil ur...

the echinoid fauna of basab area (aptian), northwest of kerman, is fairly rich and diverse, represented by pygaulidae, acropeltidae, emiratiidae, toxasteridae, holectypidae, stomechinidae and saleniidae. four regular echinoid species, among which three are new, assigned to genus tetragramma agassiz, are described and illustrated in the present paper. the new species are tetragramma basabensis, ...

The submicroscopic morphology of magnesian calcite skeletal units of echinoids, revealed by scanning electron microscopy, was compared with crystal orientation data obtained by x-ray methods and with macroscopic morphology. The Perischoechinoidea and the Euechinoidea differ with regard to the shapes of their trabeculae. Nearly all plates and spines are single crystals. A variety of diJfferent d...