The Echinoid Directory
Pilematechinus rathbuni (A. Agassiz, 1898) (right and lower) and Pilematechinus vesica (A. Agassiz, 1898) (left upper). Drawings of oral and posterior plating (from Mooi, R. & David, B. 1996. Phylogenetic analysis of extreme morphologies: deep-sea holasteroid echinoids. Journal of Natural History 30, 913-953).