In the above mentioned article (Janssen et al., Reference Janssen, Van Baal and Schulp2011) the caption of Figure 1 was not complete and missed a reference citation.
The corrected caption and the figure are below

Fig. 1. ‘Exploded view’ of the skeleton of Allopleuron hofmanni with colour-coded abundances, corrected for the relative number of bone elements in the animal's skeleton. Carapace and plastron reconstructions by Mulder (2003, pls 28, 34); adapted.
The author apologises for these errors.