Each year, the concentration of dissolved inorganic carbon (DIC) in the mixed layer at Station S in the Sargasso Sea decreases from winter to summer by about 30 umol/kg. The authors of this study demonstrate that by simultaneously observing changes in the stable isotopic ration of DIC, it is possible to quantify the contribution of physical and biological processes to this summer-fall drawdown. They find that biology is the dominant contrbutor to the drawdown, but that physical processes also play an important role.

In this revision of the calanoid copepod family Heterorhabdidae, 7 genera and 59 species are recognized, and 25 species are described as new. Included are keys to the genera and descriptions and illustrations of all species. A hypothesis of phylogenetic relationships is presented, and the geographic distribution of the species is discussed.

In this volume the author examines the pervasive pattern of alternation of structure and height of vertebral neural spines in the context of a larger review of axial structure in the most terrestrial of primitive Permo-Carboniferous tetrapods. He concludes that a coupled pattern of axial dorsiflexion and rotation played a significant role in primitive terrestrial locomotion.