Fig. 8
From: Developmental transformations in Jurassic driftwood crinoids
Numbers of brachials between axillaries could not secondarily change. They show certain trends along the arms and are always even in the ramulated zone. Still, the variability of these numbers and the difficulty to count them near the base of the arms (due to disarticulations and covering cirri) weakens their value as distinguishing character between Pentacrinites and Seirocrinus. (a, b, photos courtesy of Rolf Hauff, Holzmaden; c, d, photographed by Wolfgang Gerber from GPIT 1918/1)