Round to oval, scalelike siliceous microstructures from cherts in Cambrian limestones of the western Yukon Territory suggest affinity with chrysophycean algae. At least six morphotypes present include porous forms with single branching processes and nonporous oval, ringlike forms. Partially dissolved specimens may indicate a contribution to contemporaneous or early diagenetic chert formation.

Selenidium is a genus of gregarine parasites that infect the intestines of marine invertebrates and have morphological, ecological, and motility traits inferred to reflect the early evolutionary history of apicomplexans. Because the overall diversity and phylogenetic position(s) of these species remain poorly understood, we performed a species discovery survey of Selenidium from tube-forming po...

Introduction: Density is one of the critical factors in echinoderm larvae for aquaculture purposes. Echinoplutei are very sensitive to overcrowding. High culture density can lead problems with bacteria or protozoa, decreasing survival and generating abnormal morphotypes. Objective: To evaluate effect on larval growth sea urchin Arbacia dufresnii. Methods: Two days after fertilization A. dufresn...