Fig. 4 in Pyritized tube feet in a protasterid ophiuroid from the Upper Ordovician of Kentucky, U.S.A.

Fig. 4. Shape of the ventral surface of ambulacrals. The leg is parallel to the median suture; the foot articulates via the toes to the lateral. Proximal is top. A. Protasterina flexuosa (Miller and Dyer, 1878); A1, ambulacrals inside disk and proximal portions of free arms; A2, typical hour−glass shape of ambulacrals beyond the proximal portion of the disk; A3, four proximal ambulacrals for comparison with other taxa, median suture clearly sinuous*. B. Strataster ohioensis Kesling and LeVasseur, 1971 and Eugasterella logani (Hall, 1867), median suture straight to slightly sinuous. C. Bundenbachia beneckei* Stürtz, 1886; median suture straight to slightly sinuous. D. Palaeophiomyxa grandis*(Stürtz, 1886); median suture sinuous. E. Taeniaster spinosus (Billings, 1858); median suture straight to slightly sinuous. F. Bohemura jahni (Jaekel, 1903), Mastigophiura grandis* Lehmann, 1957, and Protaster sedgwickii* Forbes, 1849; median suture straight to slightly sinuous. Taxa marked "*" were reconstructed based on a study of the type material. All other reconstructions are based on published photographs.