The important mid-Telychian biozonal index species Monoclimacis griest
oniensis (Nicol, 1850) is redescribed and distinguished from two new s
pecies: Monoclimacis directa (formerly the 'Monograptus cf. griestonie
nsis' of Elles and Wood, 1911), and Monoclimacis woodae. Stratigraphic
ally, directa appears a little before griestoniensis, whilst woodae is
from the late griestoniensis to early crenulata Biozone.