Data PolicyPublications | Persons | Institutes | Projects IMIS Photogallery » References Anthocidaris crassispina (apical system) Description Apical system: The periproctal membrane is not totally covered by the plates. There are stem-like structures around the anal opening.Scale 2 mm. Author Mortensen, Theodor JPG file - 122.06 kB - 821 x 833 pixels added on 2005-02-23283 viewsFrom reference Schultz, H. (2006). Sea urchins: A guide to worldwide sha... © 2005 Mortensen, Theodor Click here to return to the thumbnails overview