Test elongate, adventitious; early chambers triserial, latei chambers biserial from a few compact textularian series through a succession of fully mnature chambers that tend toward uniseriality and may in fullest development reach a perfect uniserial stage; aperture verneuiline in initial stage, textularian in earliest biserial chambers, a lairge round or broadly elliptical orifice in full maturity above the base of the final chamber and becoming more and more nearly terminal with advanced age, terminal on late uniser-ial chambers. Holotype, Gaudryinella delrioensis n. sp. In species of Gatdryina the mature biserial chambers are characterized b5y the typical textularian aperture, a low ot moderately high and arched orifice at the base of the septal face and lying on the penultimate chamber. In species of this genus the mature biserial chamber s following the youthful triserial stage are less compact and are characterized by the round aperture that lies above the base of the septal face. Rare senile tests may exhibit one or more uniserial chambers with a round or broadly elliptical and almost terminal opening. Such senile chambers do not necessarily constitute an essential feature of this genus, but it is an expression of inherent potentialities that become the diagnostic character of Clavuvlina, in which the biserial stage is skipped or almost eliminated from the structure through rapid acceleration in its development from its earliest stage to the mature uniserial chambers.